The Project Gutenberg eBook, An Introduction to the History of Science, by Walter Libby

Transcriber's Note:

Every effort has been made to replicate this text as faithfully as possible. Some changes have been made. They are listed at the end of the text, apart from some changes of puctuation in the Index.

AN INTRODUCTION TO THE HISTORY OF SCIENCE

BY
WALTER LIBBY, M.A., Ph.D.

PROFESSOR OF THE HISTORY OF SCIENCE IN THE CARNEGIE INSTITUTE OF TECHNOLOGY

BOSTON NEW YORK CHICAGO

HOUGHTON MIFFLIN COMPANY

The Riverside Press Cambridge

COPYRIGHT, 1917, BY WALTER LIBBY
ALL RIGHTS RESERVED

The Riverside Press
CAMBRIDGE. MASSACHUSETTS
U. S. A

TO MY STUDENTS OF THE LAST TWELVE YEARS IN THE CHICAGO AND PITTSBURGH DISTRICTS THIS BOOK IS INSCRIBED IN FURTHERANCE OF THE ENDEAVOR TO INCULCATE A DEMOCRATIC CULTURE, EVER MINDFUL OF THE DAILY TASK, NOT ALTOGETHER IGNORANT OF THE ACHIEVEMENTS OF THE PAST

[PREFACE]

The history of science has something to offer to the humblest intelligence. It is a means of imparting a knowledge of scientific facts and principles to unschooled minds. At the same time it affords a simple method of school instruction. Those who understand a business or an institution best, as a contemporary writer on finance remarks, are those who have made it or grown up with it, and the next best thing is to know how it has grown up, and then watch or take part in its actual working. Generally speaking, we know best what we know in its origins.

The history of science is an aid in scientific research. It places the student in the current of scientific thought, and gives him a clue to the purpose and necessity of the theories he is required to master. It presents science as the constant pursuit of truth rather than the formulation of truth long since revealed; it shows science as progressive rather than fixed, dynamic rather than static, a growth to which each may contribute. It does not paralyze the self-activity of youth by the record of an infallible past.

It is only by teaching the sciences in their historical development that the schools can be true to the two principles of modern education, that the sciences should occupy the foremost place in the curriculum and that the individual mind in its evolution should rehearse the history of civilization.

The history of science should be given a larger place than at present in general history; for, as Bacon said, the history of the world without a history of learning is like a statue of Polyphemus with the eye out. The history of science studies the past for the sake of the future. It is a story of continuous progress. It is rich in biographical material. It shows the sciences in their interrelations, and saves the student from narrowness and premature specialization. It affords a unique approach to the study of philosophy. It gives new motive to the study of foreign languages. It gives an interest in the applications of knowledge, offers a clue to the complex civilization of the present, and renders the mind hospitable to new discoveries and inventions.

The history of science is hostile to the spirit of caste. It shows the sciences rising from daily needs and occupations, formulated by philosophy, enriching philosophy, giving rise to new industries, which react in turn upon the sciences. The history of science reveals men of all grades of intelligence and of all social ranks coöperating in the cause of human progress. It is a basis of intellectual and social homogeneity.

Science is international, English, Germans, French, Italians, Russians—all nations—contributing to advance the general interests. Accordingly, a survey of the sciences tends to increase mutual respect, and to heighten the humanitarian sentiment. The history of science can be taught to people of all creeds and colors, and cannot fail to enhance in the breast of every young man, or woman, faith in human progress and good-will to all mankind.

This book is intended as a simple introduction, taking advantage of the interests of youth of from seventeen to twenty-two years of age (and their intellectual compeers) in order to direct their attention to the story of the development of the sciences. It makes no claim to be in any sense complete or comprehensive. It is, therefore, a psychological introduction, having the mental capacity of a certain class of readers always in view, rather than a logical introduction, which would presuppose in all readers both full maturity of intellect and considerable initial interest in the history of science.

I cannot conclude this preface without thanking those who have assisted me in the preparation of this book—Sir William Osler, who read the first draft of the manuscript, and aided me with his counsel; Dr. Charles Singer, who read all the chapters in manuscript, and to whom I am indebted for advice in reference to the illustrations and for many other valuable suggestions; the officers of the Bodleian Library, whose courtesy was unfailing during the year I worked there; Professor Henry Crew, who helped in the revision of two of the chapters by his judicious criticism; Professor J. E. Rush, whose knowledge of bacteriology improved the chapter on Pasteur; Professor L. O. Grondahl, who read one of the chapters relating to the history of physics and suggested important emendations; and Dr. John A. Brashear, who contributed valuable information in reference to the activities of Samuel Pierpont Langley. I wish to express my gratitude also to Miss Florence Bonnet for aid in the correction of the manuscript.

W. Libby.

February 2, 1917.

[CONTENTS]

[ILLUSTRATIONS]

[AN INTRODUCTION TO THE HISTORY OF SCIENCE]

[CHAPTER I]

SCIENCE AND PRACTICAL NEEDS—EGYPT AND BABYLONIA

If you consult encyclopedias and special works in reference to the early history of any one of the sciences,—astronomy, geology, geometry, physiology, logic, or political science, for example,—you will find strongly emphasized the part played by the Greeks in the development of organized knowledge. Great, indeed, as we shall see in the next chapter, are the contributions to the growth of science of this highly rational and speculative people. It must be conceded, also, that the influence on Western science of civilizations earlier than theirs has come to us, to a considerable extent at least, through the channels of Greek literature.

Nevertheless, if you seek the very origins of the sciences, you will inevitably be drawn to the banks of the Nile, and to the valleys of the Tigris and the Euphrates. Here, in Egypt, in Assyria and Babylonia, dwelt from very remote times nations whose genius was practical and religious rather than intellectual and theoretical, and whose mental life, therefore, was more akin to our own than was the highly evolved culture of the Greeks. Though more remote in time, the wisdom and practical knowledge of Thebes and Memphis, Nineveh and Babylon, are more readily comprehended by our minds than the difficult speculations of Athenian philosophy.

Much that we have inherited from the earliest civilizations is so familiar, so homely, that we simply accept it, much as we may light, or air, or water, without analysis, without inquiry as to its origin, and without full recognition of how indispensable it is. Why are there seven days in the week, and not eight? Why are there sixty minutes in the hour, and why are there not sixty hours in the day? These artificial divisions of time are accepted so unquestioningly that to ask a reason for them may, to an indolent mind, seem almost absurd. This acceptance of a week of seven days and of an hour of sixty minutes (almost as if they were natural divisions of time like day and night) is owing to a tradition that is Babylonian in its origin. From the Old Testament (which is one of the greatest factors in preserving the continuity of human culture, and the only ancient book which speaks with authority concerning Babylonian history) we learn that Abraham, the progenitor of the Hebrews, migrated to the west from southern Babylonia about twenty-three hundred years before Christ. Even in that remote age, however, the Babylonians had established those divisions of time which are familiar to us. The seven days of the week were closely associated in men's thinking with the heavenly bodies. In our modern languages they are named after the sun, the moon, Mars, Mercury, Jupiter, Venus, and Saturn, which from the remotest times were personified and worshiped. Thus we see that the usage of making seven days a unit of time depends on the religious belief and astronomical science of a very remote civilization. The usage is so completely established that by the majority it is simply taken for granted.

Another piece of commonplace knowledge—the cardinal points of the compass—may be accepted, likewise, without inquiry or without recognition of its importance. Unless thrown on your own resources in an unsettled country or on unknown waters, you may long fail to realize how indispensable to the practical conduct of life is the knowledge of east and west and north and south. In this matter, again, the records of ancient civilizations show the pains that were taken to fix these essentials of science. Modern excavations have demonstrated that the sides or the corners of the temples and palaces of Assyria and Babylonia were directed to the four cardinal points of the compass. In Egypt the pyramids, erected before 3000 B.C., were laid out with such strict regard to direction that the conjecture has been put forward that their main purpose was to establish, in a land of shifting sands, east and west and north and south. That conjecture seems extravagant; but the fact that the Phɶnicians studied astronomy merely because of its practical value in navigation, the early invention of the compass in China, the influence on discovery of the later improvements of the compass, make us realize the importance of the alleged purpose of the pyramids. Without fixed points, without something to go by, men, before they had acquired the elements of astronomy, were altogether at sea. As they advanced in knowledge they looked to the stars for guidance, especially to the pole star and the imperishable star-group of the northern heavens. The Egyptians even developed an apparatus for telling the time by reference to the stars—a star-clock similar in its purpose to the sundial. By the Egyptians, also, was carefully observed the season of the year at which certain stars and constellations were visible at dawn. This was of special importance in the case of Sirius, for its heliacal rising, that is, the period when it rose in conjunction with the sun, marked the coming of the Nile flood (so important in the lives of the inhabitants) and the beginning of a new year. Not unnaturally Sirius was an object of worship. One temple is said to have been so constructed as to face that part of the eastern horizon at which this star arose at the critical season of inundation. Of another temple we are told that only at sunset at the time of the summer solstice did the sun throw its rays throughout the edifice. The fact that astronomy in Egypt as in Babylonia, where the temples were observatories, was closely associated with religion confirms the view that this science was first cultivated because of its bearing on the practical needs of the people. The priests were the preservers of such wisdom as had been accumulated in the course of man's immemorial struggle with the forces of nature.

It is well known that geometry had its origin in the valley of the Nile, that it arose to meet a practical need, and that it was in the first place, as its name implies, a measurement of the earth—a crude surveying, employed in the restoration of boundaries obliterated by the annual inundations of the river. Egyptian geometry cared little for theory. It addressed itself to actual problems, such as determining the area of a square or triangular field from the length of the sides. To find the area of a circular field, or floor, or vessel, from the length of the diameter was rather beyond the science of 2000 B.C. This was, however, a practical problem which had to be solved, even if the solution were not perfect. The practice was to square the diameter reduced by one ninth.

In all the Egyptian mathematics of which we have record there is to be observed a similar practical bent. In the construction of a temple or a pyramid not merely was it necessary to have regard to the points of the compass, but care must be taken to have the sides at right angles. This required the intervention of specialists, expert "rope-fasteners," who laid off a triangle by means of a rope divided into three parts, of three, four, and five units. The Babylonians followed much the same practice in fixing a right angle. In addition they learned how to bisect and trisect the angle. Hence we see in their designs and ornaments the division of the circle into twelve parts, a division which does not appear in Egyptian ornamentation till after the incursion of Babylonian influence.

There is no need, however, to multiply examples; the tendency of all Egyptian mathematics was, as already stated, concerned with the practical solution of concrete problems—mensuration, the cubical contents of barns and granaries, the distribution of bread, the amounts of food required by men and animals in given numbers and for given periods of time, the proportions and the angle of elevation (about 52°) of a pyramid, etc. Moreover, they worked simple equations involving one unknown, and had a hieroglyph for a million (the drawing of a man overcome with wonder), and another for ten million.

The Rhind mathematical papyrus in the British Museum is the main source of our present knowledge of early Egyptian arithmetic, geometry, and of what might be called their trigonometry and algebra. It describes itself as "Instructions for arriving at the knowledge of all things, and of things obscure, and of all mysteries." It was copied by a priest about 1600 B.C.—the classical period of Egyptian culture—from a document seven hundred years older.

Medicine, which is almost certain to develop in the early history of a people in response to their urgent needs, has been justly called the foster-mother of many sciences. In the records of Egyptian medical practice can be traced the origin of chemistry, anatomy, physiology, and botany. Our most definite information concerning Egyptian medicine belongs to the same general period as the mathematical document to which we have just referred. It is true something is known of remoter times. The first physician of whom history has preserved the name, I-em-hetep (He-who-cometh-in-peace), lived about 4500 B.C. Recent researches have also brought to light, near Memphis, pictures, not later than 2500 B.C., of surgical operations. They were found sculptured on the doorposts at the entrance to the tomb of a high official of one of the Pharaohs. The patients, as shown in the accompanying illustration, are suffering pain, and, according to the inscription, one cries out, "Do this [and] let me go," and the other, "Don't hurt me so!" Our most satisfactory data in reference to Egyptian medicine are derived, however, from the Ebers papyrus. This document displays some little knowledge of the pulse in different parts of the body, of a relation between the heart and the other organs, and of the passage of the breath to the lungs (and heart). It contains a list of diseases. In the main it is a collection of prescriptions for the eyes, ears, stomach, to reduce tumors, effect purgation, etc. There is no evidence of a tendency to homeopathy, but mental healing seems to have been called into play by the use of numerous spells and incantations. Each prescription, as in medical practice to-day, contains as a rule several ingredients. Among the seven hundred recognized remedies are to be noted poppy, castor-oil, gentian, colchicum, squills, and many other familiar medicinal plants, as well as bicarbonate of soda, antimony, and salts of lead and copper. The fat of the lion, hippopotamus, crocodile, goose, serpent, and wild goat, in equal parts, served as a prescription for baldness. In the interests of his art the medical practitioner ransacked the resources of organic and inorganic nature. The Ebers papyrus shows that the Egyptians knew of the development of the beetle from the egg, of the blow-fly from the larva, and of the frog from the tadpole. Moreover, for precision in the use of medicaments weights of very small denominations were employed.

The Egyptian embalmers relied on the preservative properties of common salt, wine, aromatics, myrrh, cassia, etc. By the use of linen smeared with gum they excluded all putrefactive agencies. They understood the virtue of extreme dryness in the exercise of their antiseptic art. Some knowledge of anatomy was involved in the removal of the viscera, and much more in a particular method they followed in removing the brain.

In their various industries the Egyptians made use of gold, silver, bronze (which on analysis is found to consist of copper, tin, and a trace of lead, etc.), metallic iron and copper and their oxides, manganese, cobalt, alum, cinnabar, indigo, madder, brass, white lead, lampblack. There is clear evidence that they smelted iron ore as early as 3400 B.C. maintaining a blast by means of leather tread-bellows. They also contrived to temper the metal, and to make helmets, swords, lance-points, ploughs, tools, and other implements of iron. Besides metallurgy they practiced the arts of weaving, dyeing, distillation. They produced soap (from soda and oil), transparent and colored glass, enamel, and ceramics. They were skilled in the preparation of leather. They showed aptitude for painting, and for the other fine arts. They were expert builders, and possessed the engineering skill to erect obelisks weighing hundreds of tons. They cultivated numerous vegetables, grains, fruits, and flowers. They had many domestic animals. In seeking the satisfaction of their practical needs they laid the foundation of geometry, botany, chemistry (named, as some think, from the Egyptian Khem, the god of medicinal herbs), and other sciences. But their practical achievements far transcended their theoretical formulations. To all time they will be known as an artistic, noble, and religious people, who cherished their dead and would not allow that the good and beautiful and great should altogether pass away.

Excavations in Assyria and Babylonia, especially since 1843, have brought to our knowledge an ancient culture stretching back four or five thousand years before the beginning of the Christian era. The records of Assyria and Babylonia, like those of Egypt, are fragmentary and still in need of interpretation. Here again, however, it is the fundamental, the indispensable, the practical forms of knowledge that stand revealed rather than the theoretical, speculative, and purely intellectual.

By the Babylonian priests the heavens were made the object of expert observation as early as 3800 B.C. The length of the year, the length of the month, the coming of the seasons, the course of the sun in the heavens, the movements of the planets, the recurrence of eclipses, comets, and meteors, were studied with particular care. One motive was the need of a measurement of time, the same motive as underlies the common interest in the calendar and almanac. It was found that the year contained more than 365 days, the month (synodic) more than 29 days, 12 hours, and 44 minutes. The sun's apparent diameter was contained 720 times in the ecliptic, that is, in the apparent path of the sun through the heavens. Like the Egyptians, the Babylonians took special note of the stars and star-groups that were to be seen at dawn at different times of the year. These constellations, lying in the imaginary belt encircling the heavens on either side of the ecliptic, bore names corresponding to those we have adopted for the signs of the zodiac,—Balance, Ram, Bull, Twins, Scorpion, Archer, etc. The Babylonian astronomers also observed that the successive vernal (or autumnal) equinoxes follow each other at intervals of a few seconds less than a year.

A second motive that influenced the Babylonian priests in studying the movements of the heavenly bodies was the hope of foretelling events. The planets, seen to shift their positions with reference to the other heavenly bodies, were called messengers, or angels. The appearance of Mars, perhaps on account of its reddish color, was associated in their imaginations with war. Comets, meteors, and eclipses were considered as omens portending pestilence, national disaster, or the fate of kings. The fortunes of individuals could be predicted from a knowledge of the aspect of the heavens at the hour of their birth. This interest in astrology, or divination by means of the stars, no doubt stimulated the priests to make careful observations and to preserve religiously the record of astronomical phenomena. It was even established that there is a cycle in which eclipses, solar and lunar, repeat themselves, a period (saros) somewhat more than eighteen years and eleven months. Moreover, from the Babylonians we derive some of our most sublime religious and scientific conceptions. They held that strict law governs the apparently erratic movements of the heavenly bodies. Their creation myth proclaims: "Merodach next arranged the stars in order, along with the sun and moon, and gave them laws which they were never to transgress."

The mathematical knowledge of the Babylonians is related on the one hand to their astronomy and on the other to their commercial pursuits. They possessed highly developed systems of measuring, weighing, and counting—processes, which, as we shall see in the sequel, are essential to scientific thought. About 2300 B.C. they had multiplication tables running from 1 to 1350, which were probably used in connection with astronomical calculations. Unlike the Egyptians they had no symbol for a million, though the "ten thousand times ten thousand" of the Bible (Daniel VII: 10) may indicate that the conception of even larger numbers was not altogether foreign to them. They counted in sixties as well as in tens. Their hours and minutes had each sixty subdivisions. They divided the circle into six parts and into six-times-sixty subdivisions. Tables of squares and cubes discovered in southern Babylonia were interpreted correctly only on a sexagesimal basis, the statement that 1 plus 4 is the square of 8 implying that the first unit is 60. As we have already seen, considerable knowledge of geometry is apparent in Babylonian designs and constructions.

According to a Greek historian of the fifth century B.C., there were no physicians at Babylon, while a later Greek historian (of the first century B.C.) speaks of a Babylonian university which had attained celebrity, and which is now believed to have been a school of medicine. Modern research has made known letters by a physician addressed to an Assyrian king in the seventh century B.C. referring to the king's chief physician, giving directions for the treatment of a bleeding from the nose from which a friend of the prince was suffering, and reporting the probable recovery of a poor fellow whose eyes were diseased. Other letters from the same general period mention the presence of physicians at court. We have even recovered the name (Ilu-bani) of a physician who lived in southern Babylonia about 2700 B.C. The most interesting information, however, in reference to Babylonian medicine dates from the time of Hammurabi, a contemporary of the patriarch Abraham. It appears from the code drawn up in the reign of that monarch that the Babylonian surgeons operated in case of cataract; that they were entitled to twenty silver shekels (half the sum for which Joseph was sold into slavery, and equivalent to seven or eight dollars) for a successful operation; and that in case the patient lost his life or his sight as the result of an unsuccessful operation, the surgeon was condemned to have his hands amputated.

The Babylonian records of medicine like those of astronomy reveal the prevalence of many superstitious beliefs. The spirits of evil bring maladies upon us; the gods heal the diseases that afflict us. The Babylonian books of medicine contained strange interminglings of prescription and incantation. The priests studied the livers of sacrificial animals in order to divine the thoughts of the gods—a practice which stimulated the study of anatomy. The maintenance of state menageries no doubt had a similar influence on the study of the natural history of animals.

The Babylonians were a nation of agriculturists and merchants. Sargon of Akkad, who founded the first Semitic empire in Asia (3800 B.C.), was brought up by an irrigator, and was himself a gardener. Belshazzar, the son of the last Babylonian king, dealt in wool on a considerable scale. Excavation in the land watered by the Tigris and Euphrates tells the tale of the money-lenders, importers, dyers, fullers, tanners, saddlers, smiths, carpenters, shoemakers, stonecutters, ivory-cutters, brickmakers, porcelain-makers, potters, vintners, sailors, butchers, engineers, architects, painters, sculptors, musicians, dealers in rugs, clothing and fabrics, who contributed to the culture of this great historic people. It is not surprising that science should find its matrix in so rich a civilization.

The lever and the pulley, lathes, picks, saws, hammers, bronze operating-lances, sundials, water-clocks, the gnomon (a vertical pillar for determining the sun's altitude) were in use. Gem-cutting was highly developed as early as 3800 B.C. The Babylonians made use of copper hardened with antimony and tin, lead, incised shells, glass, alabaster, lapis-lazuli, silver, and gold. Iron was not employed before the period of contact with Egyptian civilization. Their buildings were furnished with systems of drains and flushes that seem to us altogether modern. Our museums are enriched by specimens of their handicraft—realistic statuary in dolerite of 2700 B.C.; rock crystal worked to the form of a plano-convex lens, 3800 B.C.; a beautiful silver vase of the period 3950 B.C.; and the head of a goat in copper about 4000 B.C.

Excavation has not disclosed nor scholarship interpreted the full record of this ancient people in the valley of the Tigris and the Euphrates, not far from the Gulf of Persia, superior in religious inspiration, not inferior in practical achievements to the Egyptians. Both these great nations of antiquity, however, failed to carry the sciences that arose in connection with their arts to a high degree of generalization. That was reserved for another people of ancient times, namely, the Greeks.

REFERENCES

F. H. Garrison, An Introduction to the History of Medicine.

H. V. Hilprecht, Excavations in Assyria and Babylonia.

Max Neuburger, History of Medicine.

A. H. Sayce, Babylonians and Assyrians.

[CHAPTER II]

THE INFLUENCE OF ABSTRACT THOUGHT—GREECE: ARISTOTLE

No sooner did the Greeks turn their attention to the sciences which had originated in Egypt and Babylonia than the characteristic intellectual quality of the Hellenic genius revealed itself. Thales (640-546 B.C.), who is usually regarded as the first of the Greek philosophers, was the founder of Greek geometry and astronomy. He was one of the seven "wise men" of Greece, and might be called the Benjamin Franklin of antiquity, for he was interested in commerce, famous for political sagacity, and honored for his disinterested love of general truth. His birthplace was Miletus, a Greek city on the coast of Asia Minor. There is evidence that he acquired a knowledge of Babylonian astronomy. The pursuit of commerce carried him to Egypt, and there he gained a knowledge of geometry. Not only so, but he was able to advance this study by generalizing and formulating its truths. For the Egyptians, geometry was concerned with surfaces and dimensions, with areas and cubical contents; for the Greek, with his powers of abstraction, it became a study of line and angle. For example, Thales saw that the angles at the base of an isosceles triangle are equal, and that when two straight lines cut one another the vertically opposite angles are equal. However, after having established general principles, he showed himself capable of applying them to the solution of particular problems. In the presence of the Egyptian priests, to which class he was solely indebted for instruction, Thales demonstrated a method of measuring the height of a pyramid by reference to its shadow. And again, on the basis of his knowledge of the relation of the sides of a triangle to its angles, he developed a practical rule for ascertaining the distance of a ship from the shore.

The philosophical mind of Thales laid hold, no doubt, of some of the essentials of astronomical science. The particulars usually brought forward to prove his originality tend rather to show his indebtedness to the Babylonians. The number of days in the year, the length of the synodic month, the relation of the sun's apparent diameter to the ecliptic, the times of recurrence of eclipses, were matters that had long been known to the Babylonians, as well as to the Chinese. However, he aroused great interest in astronomy among the Greeks by the prediction of a solar eclipse. This was probably the eclipse of 585 B.C., which interrupted a fierce battle between the Medes and the Lydians. The advice of Thales to mariners to steer by the Lesser Bear, as nearer the pole, rather than by the Great Bear, shows also that in his astronomical studies as in his geometrical he was not indifferent to the applications of scientific knowledge.

In fact, some writers maintain that Thales was not a philosopher at all, but rather an astronomer and engineer. We know very little of his purely speculative thought. We do know, however, that he arrived at a generalization—fantastic to most minds—that all things are water. Attempts have been made to add to this statement, and to explain it away. Its great interest for the history of thought lies in the fact that it is the result of seeking the constant in the variable, the unitary principle in the multiple phenomena of nature. This abstract and general view (though perhaps suggested by the Babylonian belief that the world originated in a watery chaos, or by the teaching of Egyptian priests) was preëminently Greek, and was the first of a series of attempts to discover the basis or origin of all things. One of the followers of Thales taught that air was the fundamental principle; while Heraclitus, anticipating to some extent modern theories of the origin of the cosmos, declared in favor of a fiery vapor subject to ceaseless change. Empedocles, the great philosopher-physician, first set forth the doctrine of the four elements—earth, air, fire, and water. For Democritus indivisible particles or atoms are fundamental to all phenomena. It is evident that the theory of Thales was a starting point for Greek abstract thought, and that his inclination to seek out principles and general laws accounts for his influence on the development both of philosophy and the sciences.

Pythagoras, on the advice of Thales, visited Egypt in the pursuit of mathematics. There is reason to believe that he also visited Babylonia. For him and his followers mathematics became a philosophy—almost a religion. They had discovered (by experimenting with the monochord, the first piece of physical-laboratory apparatus, consisting of a tense harpstring with a movable bridge) the effect on the tone of the string of a musical instrument when the length is reduced by one half, and also that strings of like thickness and under equal tension yield harmonious tones when their lengths are related as 1:2, 2:3, 3:4, 4:5. The Pythagoreans drew from this the extravagant inference that the heavenly bodies would be in distance from the earth as 1, 2, 3, 4, 5, etc. Much of their theory must seem to the modern mind merely fanciful and unsupported speculation. At the same time it is only just to this school of philosophers to recognize that their assumption that simple mathematical relationships govern the phenomena of nature has had an immense influence on the advance of the sciences. Whether their fanaticism for number was owing to the influence of Egyptian priests or had an Oriental origin, it gave to the Pythagoreans an enthusiasm for pure mathematics. They disregarded the bearing of their science on the practical needs of life. Old problems like squaring the circle, trisecting the angle, and doubling the cube, were now attempted in a new spirit and with fresh vigor. The first, second, and fourth books of Euclid are largely of Pythagorean origin. For solid geometry as a science we are also indebted to this sect of number-worshipers. One of them (Archytas, 428-347 B.C., a friend of Plato) was the first to apply geometry to mechanics. We see again here, as in the case of Thales, that the love of abstract thought, the pursuit of science as science, did not interfere with ultimate practical applications.

Plato (429-347 B.C.), like many other Greek philosophers, traveled extensively, visiting Asia Minor, Egypt, and Lower Italy, where Pythagorean influence was particularly strong. His chief interest lay in speculation. For him there were two worlds, the world of sense and the world of ideas. The senses deceive us; therefore, the philosopher should turn his back upon the world of sensible impressions, and develop the reason. In his Dialogues he outlined a course of training and study, the professed object of which was to educate a class of philosophers. (Strange to say, Plato's curriculum, planned originally for the intellectual élite, still dictates in our schools the education of millions of boys and girls whose careers do not call for a training merely of the reason.)

Over the porch of his school, the Academy at Athens, were inscribed the words, "Let no one who is unacquainted with geometry enter here." It was not because it was useful in everyday life that Plato laid such insistence on this study, but because it increased the students' powers of abstraction and trained the mind to correct and vigorous thinking. From his point of view the chief good of geometry is lost unless we can through it withdraw the mind from the particular and the material. He delighted in clearness of conception. His main scientific interest was in astronomy and mathematics. We owe to him the definition of a line as "length without breadth," and the formulation of the axiom, "Equals subtracted from equals leave equals."

Plato had an immediate influence in stimulating mathematical studies, and has been called a maker of mathematicians. Euclid, who was active at Alexandria toward the end of the fourth century B.C., was not one of Plato's immediate disciples but shared the great philosopher's point of view. The story is told that one of his pupils, arrived perhaps at the pons asinorum, asked, "What do I get by learning these things?" Euclid, calling his servant, said, "Give him sixpence, since he must make gain out of what he learns." Adults were also found, even among the nimble-witted Greeks, to whom abstract reasoning was not altogether congenial. This is attested by the familiar story of Ptolemy, King of Egypt, who once asked Euclid whether geometry could not be learned in some easier way than by studying the geometer's book, The Elements. To this the schoolmaster replied, "There is no royal road to geometry." For the academic intelligence abstract and abstruse mathematics are tonic and an end in themselves. As already stated, their ultimate practical value is also immense. One of Plato's associates, working under his direction, investigated the curves produced by cutting cones of different kinds in a certain plane. These curves—the ellipse, the parabola, hyperbola—play a large part in the subsequent history of astronomy and mechanics. Another Platonist made the first measurement of the earth's circumference.

Aristotle, the greatest pupil of Plato, was born at Stagira in 384 B.C. He came of a family of physicians, was trained for the medical profession, and had his attention early directed to natural phenomena. He entered the Academy at Athens about 367 B.C., and studied there till the death of Plato twenty years later. He was a diligent but, as was natural, considering the character of his early education, by no means a passive student. Plato said that Aristotle reacted against his instructor as a vigorous colt kicks the mother that nourishes it. The physician's son did not accept without modification the view that the philosopher should turn his back upon the things of sense. He had been trained in the physical science of the time, and believed in the reality of concrete things. At the same time he absorbed what he found of value in his master's teachings. He thought that science did not consist in a mere study of individual things, but that we must pass on to a formulation of general principles and then return to a study of the concrete. His was a great systematizing intellect, which has left its imprint on nearly every department of knowledge. Physical astronomy, physical geography, meteorology, physics, chemistry, geology, botany, anatomy, physiology, embryology, and zoölogy were enriched by his teaching. It was through him that logic, ethics, psychology, rhetoric, æsthetics, political science, zoölogy (especially ichthyology), first received systematic treatment. As a great modern philosopher has said, Aristotle pressed his way through the mass of things knowable, and subjected its diversity to the power of his thought. No wonder that for ages he was known as "The Philosopher," master of those who know. His purpose was to comprehend, to define, to classify the phenomena of organic and inorganic nature, to systematize the knowledge of his own time.

Twenty years' apprenticeship in the school of Plato had sharpened his logical powers and added to his stock of general ideas, but had not taught him to distrust his senses. When we say that our eyes deceive us, we really confess that we have misinterpreted the data that our sight has furnished. Properly to know involves the right use of the senses as well as the right use of reason. The advance of science depends on the development both of speculation and observation. Aristotle advised investigators to make sure of the facts before seeking the explanation of the facts. Where preconceived theory was at variance with observed facts, the former must of course give way. Though it has been said that while Plato was a dreamer, Aristotle was a thinker, yet it must be acknowledged in qualification that Plato often showed genuine knowledge of natural phenomena in anatomy and other departments of study, and that Aristotle was carried away at times by his own presuppositions, or failed to bring his theories to the test of observation. The Stagirite held that the velocity of falling bodies is proportional to their weight, that the function of the diaphragm is to divide the region of the nobler from that of the animal passions, and that the brain is intended to act in opposition to the heart, the brain being formed of earthy and watery material, which brings about a cooling effect. The theory of the four elements—the hot, the cold, the moist, the dry—led to dogmatic statements with little attempt at verification. From the standpoint of modern studies it is easy to point out the mistakes of Aristotle even. Science is progressive, not infallible.

In his own time he was rather reproached for what was considered an undignified and sordid familiarity with observed facts. His critics said that having squandered his patrimony, he had served in the army, and, failing there, had become a seller of drugs. His observations on the effects of heat seem to have been drawn from the common processes of the home and the workshop. Even in the ripening of fruits heat appears to him to have a cooking effect. Heat distorts articles made of potters' clay after they have been hardened by cold. Again we find him describing the manufacture of potash and of steel. He is not disdainful of the study of the lower animals, but invites us to investigate all forms in the expectancy of discovering something natural and beautiful. In a similar spirit of scientific curiosity the Aristotelian work The Problems studies the principle of the lever, the rudder, the wheel and axle, the forceps, the balance, the beam, the wedge, as well as other mechanical principles.

In Aristotle, in fact, we find a mind exceptionally able to form clear ideas, and at the same time to observe the rich variety of nature. He paid homage both to the multiplicity and the uniformity of nature, the wealth of the phenomena and the simplicity of the law explaining the phenomena. Many general and abstract ideas (category, energy, entomology, essence, mean between extremes, metaphysics, meteorology, motive, natural history, principle, syllogism) have through the influence of Aristotle become the common property of educated people the world over.

Plato was a mathematician and an astronomer. Aristotle was first and foremost a biologist. His books treated the history of animals, the parts of animals, the locomotion of animals, the generation of animals, respiration, life and death, length and shortness of life, youth and old age. His psychology is, like that of the present day, a biological psychology. In his contributions to biological science is manifested his characteristic inclination to be at once abstract and concrete. His works display a knowledge of over five hundred living forms. He dissected specimens of fifty different species of animals. One might mention especially his minute knowledge of the sea-urchin, of the murex (source of the famous Tyrian dye), of the chameleon, of the habits of the torpedo, the so-called fishing-frog, and nest-making fishes, as well as of the manner of reproduction of whales and certain species of sharks. One of his chief contributions to anatomy is the description of the heart and of the arrangement of the blood-vessels. A repugnance to the dissection of the human body seems to have checked to some extent his curiosity in reference to the anatomy of man, but he was acquainted with the structure of the internal ear, the passage leading from the pharynx to the middle ear, and the two outer membranes of the brain of man. Aristotle's genius did not permit him to get lost in the mere details of observed phenomena. He recognized resemblances and differences between the various species, classified animals as belonging to two large groups, distinguished whales and dolphins from fishes, recognized the family likeness of the domestic pigeon, the wood pigeon, the rock pigeon, and the turtle dove. He laid down the characteristics of the class of invertebrates to which octopus and sepia belong. Man takes a place in Aristotle's system of nature as a social animal, the highest type of the whole series of living beings, characterized by certain powers of recall, reason, deliberation. Of course it was not to be expected that Aristotle should work out a fully satisfactory classification of all the varieties of plants and animals known to him. Yet his purpose and method mark him as the father of natural science. He had the eye to observe and the mind to grasp the relationships and the import of what he observed. His attempt to classify animals according to the nature of their teeth (dentition) has been criticized as unsuccessful, but this principle of classification is still of use, and may be regarded as typical of his mind, at once careful and comprehensive.

One instance of Aristotle's combining philosophical speculation with acute observation of natural phenomena is afforded by his work on generation and development. He knew that the transmission of life deserves special study as the predominant function of the various species of plants and animals. Deformed parents may have well-formed offspring. Children may resemble grandparents rather than parents. It is only toward the close of its development that the embryo exhibits the characteristics of its parent species. Aristotle traced with some care the embryological development of the chick from the fourth day of incubation. His knowledge of the propagation of animals was, however, not sufficient to make him reject the belief in spontaneous generation from mud, sand, foam, and dew. His errors are readily comprehensible, as, for example, in attributing spontaneous generation to eels, the habits and mode of reproduction of which only recent studies have made fully known. In regard to generation, as in other scientific fields, the philosophic mind of Aristotle anticipated modern theories, and also raised general questions only to be solved by later investigation of the facts.

Only one indication need be given of the practical results that flowed from Aristotle's scientific work. In one of his writings he has stated that the sphericity of the earth can be observed from the fact that its shadow on the moon at the time of eclipse is an arc. That it is both spherical and small in comparison with the heavenly bodies appears, moreover, from this, that stars visible in Egypt are invisible in countries farther north; while stars always above the horizon in northern countries are seen to set from countries to the south. Consequently the earth is not only spherical but also not large; otherwise this phenomenon would not present itself on so limited a change of position on the part of the observer. "It seems, therefore, not incredible that the region about the Pillars of Hercules [Gibraltar] is connected with that of India, and that there is thus only one ocean." It is known that this passage from The Philosopher influenced Columbus in his undertaking to reach the Orient by sailing west from the coast of Spain.

We must pass over Aristotle's observation of a relationship (homology) between the arms of man, the forelegs of quadrupeds, the wings of birds, and the pectoral fins of fishes, as well as many other truths to which his genius for generalization led him.

In the field of botany Aristotle had a wide knowledge of natural phenomena, and raised general questions as to mode of propagation, nourishment, relation of plants to animals, etc. His pupil and lifelong friend, and successor as leader of the Peripatetic school of philosophy, Theophrastus, combined a knowledge of mathematics, astronomy, botany, and mineralogy. His History of Plants describes about five hundred species. At the same time he treats the general principles of botany, the distribution of plants, the nourishment of the plant through leaf as well as root, the sexuality of date palm and terebinth. He lays great stress on the uses of plants. His classification of plants is inferior to Aristotle's classification of animals. His views in reference to spontaneous generation are more guarded than those of his master. His work On Stones is dominated by the practical rather than the generalizing spirit. It is evidently inspired by a knowledge of mines, such as the celebrated Laurium, from which Athens drew its supply of silver, and the wealth from which enabled the Athenians to develop a sea-power that overmatched that of the Persians. Even to-day enough remains of the galleries, shafts, scoria, mine-lamps, and other utensils to give a clear idea of this scene of ancient industry. Theophrastus considered the medicinal uses of minerals as well as of plants.

We have failed to mention Hippocrates (460-370 B.C.), the Father of Medicine, in whom is found an intimate union of practical science and speculative philosophy. We must also pass over such later Greek scientists as Aristarchus and Hipparchus who confuted the theories of Pythagoras and Plato in reference to the relative distances of the heavenly bodies from the earth. Archimedes of Syracuse demands, however, particular consideration. He lived in the third century B.C., and has been called the greatest mathematician of antiquity. In him we find the devotion to the abstract that marked the Greek intelligence. He went so far as to say that every kind of art is ignoble if connected with daily needs. His interest lay in abstruse mathematical problems. His special pride was in having determined the relative dimensions of the sphere and the enclosing cylinder. He worked out the principle of the lever. "Give me," he said, "a place on which to stand and I will move the earth." He approximated more closely than the Egyptians the solution of the problem of the relation between the area of a circle and the radius. His work had practical value in spite of himself. At the request of his friend the King of Sicily, he applied his ingenuity to discover whether a certain crown were pure gold or alloyed with silver, and he hit upon a method which has found many applications in the industries. His name is associated with the endless screw. In fact, his practical contrivances won such repute that it is not easy to separate the historical facts from the legends that enshroud his name. He aided in the defense of his native city against the Romans in 212 B.C., and devised war-engines with which to repel the besiegers. After the enemy had entered the city, says tradition, he stood absorbed in a mathematical problem which he had diagrammed on the sand. As a rude Roman soldier approached, Archimedes cried, "Don't spoil my circles," and was instantly killed. The victorious general, however, buried him with honor, and on the tomb of the mathematician caused to be inscribed the sphere with its enclosing cylinder. The triumphs of Greek abstract thought teach the lesson that practical men should pay homage to speculation even when they fail to comprehend a fraction of it.

REFERENCES

Aristotle, Historia Animalium; translated by D'A. W. Thompson. (Vol. IV of the Works of Aristotle Translated into English. Oxford: Clarendon Press.)

A. B. Buckley (Mrs. Buckley Fisher), A Short History of Natural Science.

G. H. Lewes, Aristotle; A Chapter in the History of Science.

T. E. Lones, Aristotle's Researches in Natural Science.

D'A. W. Thompson, On Aristotle as a Biologist.

William Whewell, History of the Inductive Sciences.

Alfred Weber, History of Philosophy.

[CHAPTER III]

SCIENTIFIC THEORY SUBORDINATED TO APPLICATION—ROME: VITRUVIUS

Vitruvius was a cultured engineer and architect. He was employed in the service of the Roman State at the time of Augustus, shortly before the beginning of the Christian era. He planned basilicas and aqueducts, and designed powerful war-engines capable of hurling rocks weighing three or four hundred pounds. He knew the arts and the sciences, held lofty ideals of professional conduct and dignity, and was a diligent student of Greek philosophy.

We know of him chiefly from his ten short books on Architecture (De Architectura, Libri Decem), in which he touches upon much of the learning of his time. Architecture for Vitruvius is a science arising out of many other sciences. Practice and theory are its parents. The merely practical man loses much by not knowing the background of his activities; the mere theorist fails by mistaking the shadow for the substance. Vitruvius in the theoretical and historical parts of his book draws largely on Greek writers; but in the parts bearing on practice he sets forth, with considerable shrewdness, the outcome of years of thoughtful professional experience. One cannot read his pages without feeling that he is more at home in the concrete than in the abstract and speculative, in describing a catapult than in explaining a scientific theory or a philosophy. He was not a Plato or an Archimedes, but an efficient officer of State, conscious of indebtedness to the great scientists and philosophers. With a just sense of his limitations he undertook to write, not as a literary man, but as an architect. His education had been mainly professional, but, the whole circle of learning being one harmonious system, he had been drawn to many branches of knowledge in so far as they were related to his calling.

In the judgment of Vitruvius an architect should be a good writer, able to give a lucid explanation of his plans, a skillful draftsman, versed in geometry and optics, expert at figures, acquainted with history, informed in the principles of physics and of ethics, knowing something of music (tones and acoustics), not ignorant of law, or of hygiene, or of the motions, laws, and relations to each other of the heavenly bodies. For, since architecture "is founded upon and adorned with so many different sciences, I am of opinion that those who have not, from their early youth, gradually climbed up to the summit, cannot without presumption, call themselves masters of it."

Vitruvius was far from sharing the view of Archimedes that art which was connected with the satisfaction of daily needs was necessarily ignoble and vulgar. On the contrary, his interest centered in the practical; and he was mainly concerned with scientific theory by reason of its application in the arts. Geometry helped him plan a staircase; a knowledge of tones was necessary in discharging catapults; law dealt with boundary-lines, sewage-disposal, and contracts; hygiene enabled the architect to show a Hippocratic wisdom in the choice of building-sites with due reference to airs and waters. Vitruvius had the Roman practical and regulative genius, not the abstract and speculative genius of Athens.

The second book begins with an account of different philosophical views concerning the origin of matter, and a discussion of the earliest dwellings of man. Its real theme, however, is building-material—brick, sand, lime, stone, concrete, marble, stucco, timber, pozzolano. In reference to the last (volcanic ash combined with lime and rubble to form a cement) Vitruvius writes in a way that indicates a discriminating knowledge of geological formations. Likewise his discussion of the influence of the Apennines on the rainfall, and, consequently, on the timber of the firs on the east and west of the range, shows a grasp of meteorological principles. His real power to generalize is shown in connection with his specialty, in his treatment of the sources of building-material, rather than in his consideration of the origin of matter.

Similarly the fifth book begins with a discussion of the theories of Pythagoras, but its real topic is public buildings—fora, basilicas, theaters, baths, palæstras, harbors, and quays. In the theaters bronze vases of various sizes, arranged according to Pythagorean musical principles, were to be used in the auditorium to reinforce the voice of the actor. (This recommendation was misunderstood centuries later, when Vitruvius was considered of great authority, and led to the futile practice of placing earthenware jars beneath the floors of church choirs.) According to our author, "The voice arises from flowing breath, sensible to the hearing through its percussion on the air." It is compared to the wavelets produced by a stone dropped in water, only that in the case of sound the waves are not confined to one plane. This generalization concerning the nature of sound was probably not original, however; it may have been suggested to Vitruvius by one of the Aristotelian writings.

The seventh book treats of interior decoration—mosaic floors, gypsum mouldings, wall painting, white lead, red lead, verdigris, mercury (which may be used to recover gold from worn-out pieces of embroidery), encaustic painting with hot wax, colors (black, blue, genuine and imitation murex purple). The eighth book deals with water and with hydraulic engineering, hot springs, mineral waters, leveling instruments, construction of aqueducts, lead and clay piping. Vitruvius was not ignorant of the fact that water seeks its own level, and he even argued that air must have weight in order to account for the rise of water in pumps. In his time it was more economical to convey the hard water by aqueducts than by such pipes as could then be constructed. The ninth book undertakes to rehearse the elements of geometry and astronomy—the signs of the zodiac, the sun, moon, planets, the phases of the moon, the mathematical divisions of the gnomon, the use of the sundial, etc. One feels in reading Vitruvius that his purpose was to turn to practical account what he had gained from the study of the sciences; and, at the same time, one is convinced that his applications tend to react on theoretical knowledge, and lead to new insights through the suggestion of new problems.

The tenth book of the so-called De Architectura is concerned with machinery—windmills, windlasses, axles, pulleys, cranes, pumps, fire-engines, revolving spiral tubes for raising water, wheels for irrigation worked by water-power, wheels to register distance traveled by land or water, scaling-ladders, battering-rams, tortoises, catapults, scorpions, and ballistæ. On the subject of war-engines Vitruvius speaks with special authority, as he had served, probably as military engineer, under Julius Cæsar in 46 B.C., and had been appointed superintendent of ballistæ and other military engines in the time of Augustus. It was to the divine Emperor that his book was dedicated as a protest against the administration of Roman public works. In its pages we see reflected the life of a nation employed in conquering and ruling the world, with a genius more distinguished for practical achievement than for theory and speculation. Its author is truly representative of Roman culture, for nearly everything that Rome had of a scientific and intellectual sort it drew from Greece, and it selected that part of Greek wisdom that ministered to the daily needs of the times. In his work on architecture, Vitruvius shows himself a diligent and devoted student of the sciences in order that he may turn them to account in his own department of technology.

If you glance at the study of mathematics, astronomy, and medicine among the Romans prior to the time of Greek influence, you find that next to nothing had been accomplished. Their method of field measurement was far less developed than the ancient Egyptian geometry, and even for it (as well as for their system of numerals) they were indebted to the Etruscans. The history of astronomy has nothing to record of scientific accomplishment on the part of the Romans. They reckoned time by months, and in the earlier period kept a rude tally of the years by driving nails into a statue of Janus, the ancient sun-god. As we shall see, they were unable to regulate the calendar. Again, so far were they from contributing to the development of medicine that they had no physicians for the six hundred years preceding the coming of Greek science. A medical slave acted as overseer of the family health, and disease was combated in primitive fashion by prayers and offerings to various gods, who were supposed to furnish general health or to influence the functions of the different parts of the body. So rude was the native culture of the Romans that it is doubtful whether they had any schools before the advent of Greek learning. The girls were trained by their mothers, the boys either by their fathers or by some master to whom they were apprenticed.

The Greeks were conquered by the Romans in 146 B.C., but before that time Roman life and institutions had been touched by Hellenic culture. Cato the Censor (who died in 149 B.C.) and other conservatives tried in vain to resist the invasion of Greek science, philosophy, and refinement. After the conquest of Greece the master became pupil, and the conqueror was taken captive. The Romans, however, never rose to preëminence in science or the fine arts. A further development in technology corresponded more closely to their national needs, and in this field they came undoubtedly to surpass the Greeks. Bridges, ships, military roads, war-engines, aqueducts, public buildings, organization of the State and the army, the formulation of legal procedure, the enactment and codification of laws, were necessary to secure and maintain the Empire. The use in building construction of a knowledge of the right-angled triangle as well as other matters known to the Egyptians and Babylonians, and Archimedes' method of determining specific gravity were of peculiar interest to the practical Romans.

Julius Cæsar, 102-44 B.C., instituted a reform of the calendar. This was very much needed, as the Romans were eighty-five days out of their reckoning, and the date for the spring equinox, instead of coming at the proper time, was falling in the middle of winter. An Alexandrian astronomer (Sosigenes) assisted in establishing the new (Julian) calendar. The principle followed was based on ancient Egyptian practice. Among the 365 days of the year was to be inserted, or intercalated, every fourth year an extra day. This the Romans did by giving to two days in leap-year the same name; thus the sixth day before the first of March was repeated, and leap-year was known as a bissextile year. Cæsar, trained himself in the Greek learning and known to his contemporaries as a writer on mathematics and astronomy, also planned a survey of the Empire, which was finally carried into execution by Augustus.

There is evidence that the need of technically trained men became more and more pressing as the Empire developed. At first there were no special teachers or schools. Later we find mention of teachers of architecture and mechanics. Then the State came to provide classrooms for technical instruction and to pay the salaries of the teachers. Finally, in the fourth century A.D., further measures were adopted by the State. The Emperor Constantine writes to one of his officials: "We need as many engineers as possible. Since the supply is small, induce to begin this study youths of about eighteen years of age who are already acquainted with the sciences required in a general education. Relieve their parents from the payment of taxes, and furnish the students with ample means."

Pliny the Elder (23-79 A.D.), in the encyclopedic work which he compiled under the title Natural History, drew freely on hundreds of Greek and Latin authors for his facts and fables. In the selection that he made from his sources can be traced, as in the work of Vitruvius and other Latin writers, the tendency to make the sciences subservient to the arts. For example, the one thousand species of plants of which he makes mention are considered from the medicinal or from the economic point of view. It was largely in the interest of their practical uses that the Roman regarded both plants and animals; his chief motive was not a disinterested love of truth. Pliny thought that each plant had its special virtue, and much of his botany is applied botany. So comprehensive a work as the Natural History was sure to contain interesting anticipations of modern science. Pliny held that the earth hovers in the heavens upheld by the air, that its sphericity is proved by the fact that the mast of a ship approaching the land is visible before the hull comes in sight. He also taught that there are inhabitants on the other side of the earth (antipodes), that at the time of the winter solstice the polar night must last for twenty-four hours, and that the moon plays a part in the production of the tides. Nevertheless, the whole book is permeated by the idea that the purpose of nature is to minister to the needs of man.

It further marks the practical spirit among the Romans that a work on agriculture by a Carthaginian (Mago) was translated by order of the Senate. Cato (234-149 B.C.), so characteristically Roman in his genius, wrote (De Re Rustica) concerning grains and the cultivation of fruits. Columella wrote treatises on agriculture and forestry. Among the technical writings of Varro besides the book on agriculture, which is extant, are numbered works on law, mensuration, and naval tactics.

It was but natural that at the time of the Roman Empire there should be great advances in medical science. A Roman's interest in a science was keen when it could be proved to have immediate bearing on practical life. The greatest physician of the time, however, was a Greek. Galen (131-201 A.D.), who counted himself a disciple of Hippocrates, began to practice at Rome at the age of thirty-three. He was the only experimental physiologist before the time of Harvey. He studied the vocal apparatus in the larynx, and understood the contraction and relaxation of the muscles, and, to a considerable extent, the motion of the blood through the heart, lungs, and other parts of the body. He was a vivisector, made sections of the brain in order to determine the functions of its parts, and severed the gustatory, optic, and auditory nerves with a similar end in view. His dissections were confined to the lower animals. Yet his works on human anatomy and physiology were authoritative for the subsequent thirteen centuries. It is difficult to say how much of the work and credit of this practical scientist is to be given to the race from which he sprang and how much to the social environment of his professional career. (In the ruins of Pompeii, destroyed in 79 A.D., have been recovered some two hundred kinds of surgical instrument, and in the later Empire certain departments of surgery developed to a degree not surpassed till the sixteenth century.) If it is too much to say that the Roman environment is responsible for Galen's achievements, we can at least say that it was characteristic of the Roman people to welcome such science as his, capable of demonstrating its utility.

Dioscorides was also a Greek who, long resident at Rome, applied his science in practice. He knew six hundred different plants, one hundred more than Theophrastus. The latter laid much stress, as we have seen in the preceding chapter, on the medicinal properties of plants, but in this respect he was outdone by Dioscorides (as well as by Pliny). Theophrastus was the founder of the science of botany, Dioscorides the founder of materia medica.

Quintilian, born in Spain, spent the greater part of his life as a teacher of rhetoric in Rome. He valued the sciences, not on their own account, but as they might subserve the purposes of the orator. Music, astronomy, logic, and even theology, might be exploited as aids to public speech. In the time of Quintilian (first century A.D.), as in our own, oratory was considered one of the great factors in a young man's success; mock debating contests were frequent, and the periods of the future orators reverberated among the seven hills of Rome. To him our schools are also indebted for the method of teaching foreign languages by declensions, conjugations, vocabularies, formal rhetoric and annotations. He considered ethics the most valuable part of philosophy.

In fact, it would not be pressing our argument unduly to say that, so far as the minds of the Romans turned to speculation, it was the tendency to practical philosophy—Epicureanism or Stoicism—that was most characteristic. This was true even of Lucretius (98-55 B.C.), author of the noble poem concerning the Nature of Things (De Rerum Natura). In this work he writes under the inspiration of Greek philosophy. His model was a poem by Empedocles on Nature, the grand hexameters of which had fascinated the Roman poet. The distinctive feature of the work of Lucretius is the purpose, ethical rather than speculative, to curb the ambition, passion, luxury of those hard pagan times, and likewise to free the souls of his countrymen from the fear of the gods and the fear of death, and to replace superstition by peace of mind and purity of heart.

From the work on Physical Science (Quæstionum Naturalium, Libri Septem) of Seneca, the tutor of Nero, we learn that the Romans made use of globes filled with water as magnifiers, employed hothouses in their highly developed horticulture, and observed the refraction of colors by the prism. At the same time the book contains interesting conjectures in reference to the relation of earthquakes and volcanoes, and to the fact that comets travel in fixed orbits. In the main, however, this work is an attempt to find a basis for ethics in natural phenomena. Seneca was a Stoic, as Lucretius was an Epicurean, moralist.

When we glance back at the culture, or cultures, of the great peoples of antiquity, Egyptian, Babylonian, Greek, and Roman, that which had its center on the banks of the Tiber offers the closest analogy to our own. Among English-speaking peoples as among the Romans there is noticeable a certain contempt for scientific studies strangely mingled with an inclination to exploit all theory in the interest of immediate application. An English author, writing in 1834, remarks that the Romans, eminent in war, in polite literature, and civil policy, showed at all times a remarkable indisposition to the pursuit of mathematical and physical science. Geometry and astronomy, so highly esteemed by the Greeks, were not merely disregarded by the Italians, but even considered beneath the attention of a man of good birth and liberal education; they were imagined to partake of a mechanical, and therefore servile, character. "The results were seen to be made use of by the mechanical artist, and the abstract principles were therefore supposed to be, as it were, contaminated by his touch. This unfortunate peculiarity in the taste of his countrymen is remarked by Cicero. And it may not be irrelevant to inquire, whether similar prejudices do not prevail to some extent even among ourselves." To Americans also must be attributed an impatience of theory as theory, and a predominant interest in the applications of science.

REFERENCES

Lucretius, The Nature of Things; translated by H. A. J. Munro.

Pliny, Natural History; translated by Philemon Holland.

Professor Baden Powell, History of Natural Philosophy.

Seneca, Physical Science; translated by John Clarke.

Vitruvius, Architecture; translated by Joseph Gwilt, 1826.

Vitruvius, Architecture; translated by Professor M. H. Morgan, 1914.

[CHAPTER IV]

THE CONTINUITY OF SCIENCE—THE MEDIEVAL CHURCH AND THE ARABS

Learning has very often and very aptly been compared to a torch passed from hand to hand. By the written sign or spoken word it is transmitted from one person to another. Very little advance in culture could be made even by the greatest man of genius if he were dependent, for what knowledge he might acquire, merely on his own personal observation. Indeed, it might be said that exceptional mental ability involves a power to absorb the ideas of others, and even that the most original people are those who are able to borrow the most freely.

In recalling the lives of certain great men we may at first be inclined to doubt this truth. How shall we account for the part played in the progress of civilization by the rustic Burns, the village-bred Shakespeare, or by Lincoln the frontiersman? When, however, we scrutinize the case of any one of these, we discover, of course, exceptional natural endowment, susceptibility to mental influence, remarkable powers of acquisition, but no ability to produce anything absolutely original. In the case of Lincoln, for example, we find that in his youth he was as distinguished by diligence in study as by physical stature and prowess. After he withdrew from school, he read, wrote, and ciphered (in the intervals of manual work) almost incessantly. He read everything he could lay hands on. He copied out what most appealed to him. A few books he read and re-read till he had almost memorized them. What constituted his library? The Bible, Æsop's Fables, Robinson Crusoe, The Pilgrim's Progress, a Life of Washington, a History of the United States. These established for him a vital relation with the past, and laid the foundations of a democratic culture; not the culture of a Chesterfield, to be sure, but something immeasurably better, and none the less good for being almost universally accessible. Lincoln developed his logical powers conning the dictionary. Long before he undertook the regular study of the law, he spent long hours poring over the revised statutes of the State in which he was living. From a book he mastered with a purpose the principles of grammar. In the same spirit he learned surveying, also by means of a book. There is no need to ignore any of the influences that told toward the development of this great statesman, the greatest of English-speaking orators, but it is evident that remote as was his habitation from all the famous centers of learning he was, nevertheless, early immersed in the current of the world's best thought.

Similarly, in the history of science, every great thinker has his intellectual pedigree. Aristotle was the pupil of Plato, Plato was the disciple of Socrates, and the latter's intellectual genealogy in turn can readily be traced to Thales, and beyond—to Egyptian priests and Babylonian astronomers.

The city of Alexandria, founded by the pupil of Aristotle in 332 B.C., succeeded Athens as the center of Greek culture. On the death of Alexander the Great, Egypt was ruled by one of his generals, Ptolemy, who assumed the title of king. This monarch, though often engaged in war, found time to encourage learning, and drew to his capital scholars and philosophers from Greece and other countries. He wrote himself a history of Alexander's campaigns, and instituted the famous library of Alexandria. This was greatly developed (and supplemented with schools of science and an observatory) by his son Ptolemy Philadelphus, a prince distinguished by his zeal in promoting the good of the human species. He collected vast numbers of manuscripts, had strange animals brought from distant lands to Alexandria, and otherwise promoted scientific research. This movement was continued under Ptolemy III (246-221 B.C.).

Something has already been said of the early astronomers and mathematicians of Alexandria. The scientific movement of the later Alexandrian period found its consummation in the geographer, astronomer, and mathematician Claudius Ptolemy (not to be confused with the rulers of that name). He was most active 127-151 A.D., and is best known by his work the Syntaxis, which summarized what was known in astronomy at that time. Ptolemy drew up a catalogue of 1080 stars based on the earlier work of Hipparchus. He followed that astronomer in teaching that the earth is the center of the movement of the heavenly bodies, and this geocentric system of the heavens became known as the Ptolemaic system of astronomy. To Hipparchus and Ptolemy we owe also the beginnings of the science of trigonometry. The Syntaxis sets forth his method of drawing up a table of chords. For example, the side of a hexagon inscribed in a circle is equal to the radius, and is the chord of 60°, or of the sixth part of the circle. The radius is divided into sixty equal parts, and these again divided and subdivided sexagesimally. The smaller divisions and the subdivisions are known as prime minute parts and second minute parts (partes minutæ primæ and partes minutæ secundæ), whence our terms "minute" and "second." The sexagesimal method of dividing the circle and its parts was, as we have seen in the first chapter, of Babylonian origin.

Ptolemy was the last of the great Greek astronomers. In the fourth century and at the beginning of the fifth, Theon and his illustrious daughter Hypatia commented on and taught the astronomy of Ptolemy. In the Greek schools of philosophy Plato's doctrine of the supreme reality of the invisible world was harmonized for a time with Christian mysticism, but these schools were suppressed at the beginning of the sixth century. The extinction of scientific and of all other learning seemed imminent.

What were the causes of this threatened break in the historical continuity of science? They were too many and too varied to admit of adequate statement here. From the latter part of the fourth century the Roman Empire had been overrun by the Visigoths, the Vandals, the Huns, the Ostrogoths, the Lombards, and other barbarians. Even before these incursions learning had suffered under the calamity of war. In the time of Julius Cæsar the larger of the famous libraries of Alexandria, containing, it is computed, some 490,000 rolls, caught fire from ships burning in the harbor, and perished. This alone involved an incalculable setback to the march of scientific thought.

Another influence tending to check the advance of the sciences was the clash between Christian and Pagan ideals. To many of the bishops of the Church the aims and pursuits of science seemed vain and trivial when compared with the preservation of purity of character or the assurance of eternal felicity. Many were convinced that the end of the world was at hand, and strove to fix their thoughts solely on the world to come. Their austere disregard of this life found some support in a noble teaching of the Stoic philosophy that death itself is no evil to the just man. The early Christian teachers held that the body should be mortified if it interfered with spiritual welfare. Disease is a punishment, or a discipline to be patiently borne. One should choose physical uncleanliness rather than run any risk of moral contamination. It is not impossible for enlightened people at the present time to assume a tolerant attitude toward the worldly Greeks or the other-worldly Christians. At that time, however, mutual antipathy was intense. The long and cruel war between science and Christian theology had begun.

Not all the Christian bishops, to be sure, took a hostile view of Greek learning. Some regarded the great philosophers as the allies of the Church. Some held that churchmen should study the wisdom of the Greeks in order the better to refute them. Others held that the investigation of truth was no longer necessary after mankind had received the revelation of the gospel. One of the ablest of the Church Fathers regretted his early education and said that it would have been better for him if he had never heard of Democritus. The Christian writer Lactantius asked shrewdly whence atoms came, and what proof there was of their existence. He also allowed himself to ridicule the idea of the antipodes, a topsy-turvy world of unimaginable disorder. In 389 A.D. one of the libraries at Alexandria was destroyed and its books were pillaged by the Christians. In 415 Hypatia, Greek philosopher and mathematician, was murdered by a Christian mob. In 642 the Arabs having pushed their conquest into northern Africa gained possession of Alexandria. The cause of learning seemed finally and irrecoverably lost.

The Arab conquerors, however, showed themselves singularly hospitable to the culture of the nations over which they had gained control. Since the time of Alexander there had been many Greek settlers in the larger cities of Syria and Persia, and here learning had been maintained in the schools of the Jews and of a sect of Christians (Nestorians), who were particularly active as educators from the fifth century to the eleventh. The principal Greek works on science had been translated into Syrian. Hindu arithmetic and astronomy had found their way into Persia. By the ninth century all these sources of scientific knowledge had been appropriated by the Arabs. Some fanatics among them, to be sure, held that one book, the Koran, was of itself sufficient to insure the well-being of the whole human race, but happily a more enlightened view prevailed.

In the time of Harun Al-Rashid (800 A.D.), and his son, the Caliphate of Bagdad was the center of Arab science. Mathematics and astronomy were especially cultivated; an observatory was established; and the work of translation was systematically carried on by a sort of institute of translators, who rendered the writings of Aristotle, Hippocrates, Galen, Euclid, Ptolemy, and other Greek scientists, into Arabic. The names of the great Arab astronomers and mathematicians are not popularly known to us; their influence is greater than their fame. One of them describes the method pursued by him in the ninth century in taking measure of the circumference of the earth. A second developed a trigonometry of sines to replace the Ptolemaic trigonometry of chords. A third made use of the so-called Arabic (really Hindu) system of numerals, and wrote the first work on Algebra under that name. In this the writer did not aim at the mental discipline of students, but sought to confine himself to what is easiest and most useful in calculation, "such as men constantly require in cases of inheritance, legacies, partition, law-suits, and trade, and in all their dealings with one another, or where the measuring of lands, the digging of canals, geometrical computation, and other objects of various sorts and kinds are concerned."

In the following centuries Arab institutions of higher learning were widely distributed and the flood-tide of Arab science was borne farther west. At Cairo about the close of the tenth century the first accurate records of eclipses were made, and tables were constructed of the motions of the sun, moon, and planets. Here as elsewhere the Arabs displayed ingenuity in the making of scientific apparatus, celestial globes, sextants of large size, quadrants of various sorts, and contrivances from which in the course of time were developed modern surveying instruments for measuring horizontal and vertical angles. Before the end of the eleventh century an Arab born at Cordova, the capital of Moorish Spain, constructed the Toletan Tables. These were followed in 1252 by the publication of the Alphonsine Tables, an event which astronomers regard as marking the dawn of European science.

Physics and chemistry, as well as mathematics and astronomy, owe much in their development to the Arabs. An Arabian scientist of the eleventh century studied the phenomena of the reflection and refraction of light, explained the causes of morning and evening twilight, understood the magnifying power of lenses and the anatomy of the human eye. Our use of the terms retina, cornea, and vitreous humor may be traced to the translation of his work on optics. The Arabs also made fair approximations to the correct specific weights of gold, copper, mercury, and lead. Their alchemy was closely associated with metallurgy, the making of alloys and amalgams, and the handicrafts of the goldsmiths and silversmiths. The alchemists sought to discover processes whereby one metal might be transmuted into another. Sulphur affected the color and substance. Mercury was supposed to play an important part in metal transmutations. They thought, for example, that tin contained more mercury than lead, and that the baser, more unhealthy metal might be converted into the nobler and more healthy by the addition of mercury. They even sought for a substance that might effect all transmutations, and be for mankind a cure for all ailments, even that of growing old. The writings that have been attributed to Geber show the advances that chemistry made through the experiments of the Arabs. They produced sulphuric and nitric acids, and aqua regia, able to dissolve gold, the king of metals. They could make use of wet methods, and form metallic salts such as silver nitrate. Laboratory processes like distilling, filtering, crystallization, sublimation, became known to the Europeans through them. They obtained potash from wine lees, soda from sea-plants, and from quicksilver the mercuric oxide which played so interesting a part in the later history of chemistry.

Much of the science lore of the Arabs arose from their extensive trade, and in the practice of medicine. They introduced sugar-cane into Europe, improved the methods of manufacturing paper, discovered a method of obtaining alcohol, knew the uses of gypsum and of white arsenic, were expert in pharmacy and learned in materia medica. They are sometimes credited with introducing to the West the knowledge of the mariner's compass and of gunpowder.

Avicenna (980-1037), the Arab physician, not only wrote a large work on medicine (the Canon) based on the lore of Galen, which was used as a text-book for centuries in the universities of Europe, but wrote commentaries on all the works of Aristotle. For Averroës (1126-1198), the Arab physician and philosopher, was reserved the title "The Commentator," due to his devotion to the works of the Greek biologist and philosopher. It was through the commentaries of Averroës that Aristotelian science became known in Europe during the Middle Ages. In his view Aristotle was the founder and perfecter of science; yet he showed an independent knowledge of physics and chemistry, and wrote on astronomy and medicine as well as philosophy. He set forth the facts in reference to natural phenomena purely in the interests of the truth. He could not conceive of anything being created from nothing. At the same time he taught that God is the essence, the eternal cause, of progress. It is in humanity that intellect most clearly reveals itself, but there is a transcendent intellect beyond, union with which is the highest bliss of the individual soul. With the death of the Commentator the culture of liberal science among the Arabs came to an end, but his influence (and through him that of Aristotle) was perpetuated in all the western centers of education.

The preservation of the ancient learning had not, however, depended solely on the Arabs. At the beginning of the sixth century, before the taking of Alexandria by the followers of Mohammed, St. Benedict had founded the monastery of Monte Cassino in Italy. Here was begun the copying of manuscripts, and the preparation of compendiums treating of grammar, dialectic, rhetoric, arithmetic, astronomy, music, and geometry. These were based on ancient, Roman writings. Works like Pliny's Natural History, the encyclopedia of the Middle Ages, had survived all the wars by which Rome had been devastated. Learning, which in Rome's darkest days had found refuge in Britain and Ireland, returned book in hand. Charlemagne (800) called Alcuin from York to instruct princes and nobles at the Frankish court. At this same palace school half a century later the Irishman Scotus Erigena exhibited his learning, wit, and logical acumen. In the tenth century Gerbert (Pope Sylvester II) learned mathematics at Arab schools in Spain. The translation of Arab works on science into the Latin language, freer intercourse of European peoples with the East through war and trade, economic prosperity, the liberation of serfs and the development of a well-to-do middle class, the voyages of Marco Polo to the Orient, the founding of universities, the encouragement of learning by the Emperor Frederick II, the study of logic by the schoolmen, were all indicative of a new era in the history of scientific thought.

The learned Dominican Albertus Magnus (1193-1280) was a careful student of Aristotle as well as of his Arabian commentators. In his many books on natural history he of course pays great deference to the Philosopher, but he is not devoid of original observation. As the official visitor of his order he had traveled through the greater part of Germany on foot, and with a keen eye for natural phenomena was able to enrich botany and zoölogy by much accurate information. His intimacy with the details of natural history made him suspected by the ignorant of the practice of magical arts.

His pupil and disciple Thomas Aquinas (1227-1274) was the philosopher and recognized champion of the Christian Church. In 1879 Pope Leo XIII, while proclaiming that every wise saying, every useful discovery, by whomsoever it may be wrought, should be welcomed with a willing and grateful mind, exhorted the leaders of the Roman Catholic Church to restore the golden wisdom of St. Thomas and to propagate it as widely as possible for the good of society and the advancement of all the sciences. Certainly the genius of St. Thomas Aquinas seems comprehensive enough to embrace all science as well as all philosophy from the Christian point of view. According to him there are two sources of knowledge, reason and revelation. These are not irreconcilably opposed. The Greek philosophers speak with the voice of reason. It is the duty of theology to bring all knowledge into harmony with the truths of revelation imparted by God for the salvation of the human race. Averroës is in error when he argues the impossibility of something being created from nothing, and again when he implies that the individual intellect becomes merged in a transcendental intellect; for such teaching would be the contrary of what has been revealed in reference to the creation of the world and the immortality of the individual soul. In the accompanying illustration we see St. Thomas inspired by Christ in glory, guided by Moses, St. Peter, and the Evangelists, and instructed by Aristotle and Plato. He has overcome the heathen philosopher Averroës, who lies below discomfited.

The English Franciscan Roger Bacon (1214-1294) deserves to be mentioned with the two great Dominicans. He was acquainted with the works of the Greek and Arabian scientists. He transmitted in a treatise that fell under the eye of Columbus the view of Aristotle in reference to the proximity of another continent on the other side of the Atlantic; he anticipated the principle on which the telescope was afterwards constructed; he advocated basing natural science on experience and careful observation rather than on a process of reasoning. Roger Bacon's writings are characterized by a philosophical breadth of view. To his mind the earth is only an insignificant dot in the center of the vast heavens.

In the centuries that followed the death of Bacon the relation of this planet to the heavenly bodies was made an object of study by a succession of scientists who like him were versed in the achievements of preceding ages. Peurbach (1423-1461), author of New Theories of the Planets, developed the trigonometry of the Arabians, but died before fulfilling his plan to give Europe an epitome of the astronomy of Ptolemy. His pupil, Regiomontanus, however, more than made good the intentions of his master. The work of Peurbach had as commentator the first teacher in astronomy of Copernicus (1473-1543). Later Copernicus spent nine years in Italy, studying at the universities and acquainting himself with Ptolemaic and other ancient views concerning the motions of the planets. He came to see that the apparent revolution of the heavenly bodies about the earth from east to west is really owing to the revolution of the earth on its axis from west to east. This view was so contrary to prevailing beliefs that Copernicus refused to publish his theory for thirty-six years. A copy of his book, teaching that our earth is not the center of the universe, was brought to him on his deathbed, but he never opened it.

Momentous as was this discovery, setting aside the geocentric system which had held captive the best minds for fourteen slow centuries and substituting the heliocentric, it was but a link in the chain of successes in astronomy to which Tycho Brahe, Kepler, Galileo, Newton, and their followers contributed.

REFERENCES

The Catholic Encyclopedia.

J. L. E. Dreyer, History of the Planetary Systems.

Encyclopædia Britannica. Arabian Philosophy; Roger Bacon.

W. J. Townsend, The Great Schoolmen of the Middle Ages.

R. B. Vaughan, St. Thomas of Aquin; his Life and Labours.

Andrew D. White, A History of the Warfare of Science with Theology in Christendom.

[CHAPTER V]

THE CLASSIFICATION OF THE SCIENCES—FRANCIS BACON

The preceding chapter has shown that there is a continuity in the development of single sciences. The astronomy, or the chemistry, or the mathematics, of one period depends so directly on the respective science of the foregoing period, that one feels justified in using the term "growth," or "evolution," to describe their progress. Now a vital relationship can be observed not only among different stages of the same science, but also among the different sciences. Physics, astronomy, and chemistry have much in common; geometry, trigonometry, arithmetic, and algebra are called "branches" of mathematics; zoölogy and botany are biological sciences, as having to do with living species. In the century following the death of Copernicus, two great scientists, Bacon and Descartes, compared all knowledge to a tree, of which the separate sciences are branches. They thought of all knowledge as a living organism with an interconnection or continuity of parts, and a capability of growth.

By the beginning of the seventeenth century the sciences were so considerable that in the interest of further progress a comprehensive view of the tree of knowledge, a survey of the field of learning, was needed. The task of making this survey was undertaken by Francis Bacon, Lord Verulam (1561-1626). His classification of human knowledge was celebrated, and very influential in the progress of science. He kept one clear purpose in view, namely, the control of nature by man. He wished to take stock of what had already been accomplished, to supply deficiencies, and to enlarge the bounds of human empire. He was acutely conscious that this was an enterprise too great for any one man, and he used his utmost endeavors to induce James I to become the patron of the plan. His project admits of very simple statement now; he wished to edit an encyclopedia, but feared that it might prove impossible without coöperation and without state support. He felt capable of furnishing the plans for the building, but thought it a hardship that he was compelled to serve both as architect and laborer. The worthiness of these plans was attested in the middle of the eighteenth century, when the great French Encyclopaedia was projected by Diderot and D'Alembert. The former, its chief editor and contributor, wrote in the Prospectus: "If we come out successful from this vast undertaking, we shall owe it mainly to Chancellor Bacon, who sketched the plan of a universal dictionary of sciences and arts at a time when there were not, so to speak, either arts or sciences. This extraordinary genius, when it was impossible to write a history of what men knew, wrote one of what they had to learn."

Bacon, as we shall amply see, was a firm believer in the study of the arts and occupations, and at the same time retained his devotion to principles and abstract thought. He knew that philosophy could aid the arts that supply daily needs; also that the arts and occupations enriched the field of philosophy, and that the basis of our generalizations must be the universe of things knowable. "For," he writes, "if men judge that learning should be referred to use and action, they judge well; but it is easy in this to fall into the error pointed out in the ancient fable; in which the other parts of the body found fault with the stomach, because it neither performed the office of motion as the limbs do, nor of sense, as the head does; but yet notwithstanding it is the stomach which digests and distributes the aliment to all the rest. So that if any man think that philosophy and universality are idle and unprofitable studies, he does not consider that all arts and professions are from thence supplied with sap and strength." For Bacon, as for Descartes, natural philosophy was the trunk of the tree of knowledge.

On the other hand, he looked to the arts, crafts, and occupations as a source of scientific principles. In his survey of learning he found some records of agriculture and likewise of many mechanical arts. Some think them a kind of dishonor. "But if my judgment be of any weight, the use of History Mechanical is, of all others, the most radical and fundamental towards natural philosophy." When the different arts are known, the senses will furnish sufficient concrete material for the information of the understanding. The record of the arts is of most use because it exhibits things in motion, and leads more directly to practice. "Upon this history, therefore, mechanical and illiberal as it may seem (all fineness and daintiness set aside), the greatest diligence must be bestowed." "Again, among the particular arts those are to be preferred which exhibit, alter, and prepare natural bodies and materials of things as agriculture, cooking, chemistry, dyeing; the manufacture of glass, enamel, sugar, gunpowder, artificial fires, paper and the like." Weaving, carpentry, architecture, manufacture of mills, clocks, etc. follow. The purpose is not solely to bring the arts to perfection, but all mechanical experiments should be as streams flowing from all sides into the sea of philosophy.

Shortly after James I came to the throne in 1603, Bacon published his Advancement of Learning. He continued in other writings, however, to develop the organization of knowledge, and in 1623 summed up his plan in the De Augmentis Scientiarum.

A recent writer (Pearson, 1900) has attempted to summarize Bacon's classification of the different branches of learning. When one compares this summary with an outline of the classification of knowledge made by the French monk, Hugo of St. Victor, who stands midway between Isidore of Seville (570-636) and Bacon, some points of resemblance are of course obvious. Moreover, Hugo, like Bacon, insisted on the importance of not being narrowly utilitarian. Men, he says, are often accustomed to value knowledge not on its own account but for what it yields. Thus it is with the arts of husbandry, weaving, painting, and the like, where skill is considered absolutely vain, unless it results in some useful product. If, however, we judged after this fashion of God's wisdom, then, no doubt, the creation would be preferred to the Creator. But wisdom is life, and the love of wisdom is the joy of life (felicitas vitæ).

Nevertheless, when we compare these classifications diligently, we find very marked differences between Bacon's views and the medieval. The weakest part of Hugo's classification is that which deals with natural philosophy. Physica, he says, undertakes the investigation of the causes of things in their effects, and of effects in their causes. It deals with the explanation of earthquakes, tides, the virtues of plants, the fierce instincts of wild animals, every species of stone, shrub, and reptile. When we turn to his special work, however, on this branch of knowledge, Concerning Beasts and Other Things, we find no attempt to subdivide the field of physica, but a series of details in botany, geology, zoölogy, and human anatomy, mostly arranged in dictionary form.

When we refer to Bacon's classification we find that Physics corresponds to Hugo's Physica. It studies natural phenomena in relation to their material causes. For this study, Natural History, according to Bacon, supplies the facts. Let us glance, then, at his work on natural history, and see how far he had advanced from the medieval toward the modern conception of the sciences.

For purposes of scientific study he divided the phenomena of the universe into (1) Celestial phenomena; (2) Atmosphere; (3) Globe; (4) Substance of earth, air, fire, water; (5) Genera, species, etc. Great scope is given to the natural history of man. The arts are classified as nature modified by man. History means, of course, descriptive science.

Bacon's Catalogue of Particular Histories by Titles (1620)

1. History of the Heavenly Bodies; or Astronomical History.
2. History of the Configuration of the Heavens and the parts thereof towards the Earth and the parts thereof; or Cosmographical History.
3. History of Comets.
4. History of Fiery Meteors.
5. History of Lightnings, Thunderbolts, Thunders, and Coruscations.
6. History of Winds and Sudden Blasts and Undulations of the Air.
7. History of Rainbows.
8. History of Clouds, as they are seen above.
9. History of the Blue Expanse, of Twilight, of Mock-Suns, Mock-Moons, Haloes, various colours of the Sun; and of every variety in the aspect of the heavens caused by the medium.
10. History of Showers, Ordinary, Stormy, and Prodigious; also of Waterspouts (as they are called); and the like.
11. History of Hail, Snow, Frost, Hoar-frost, Fog, Dew, and the like.
12. History of all other things that fall or descend from above, and that are generated in the upper region.
13. History of Sounds in the upper region (if there be any), besides Thunder.
14. History of Air as a whole, or in the Configuration of the World.
15. History of the Seasons or Temperatures of the Year, as well according to the variations of Regions as according to accidents of Times and Periods of Years; of Floods, Heats, Droughts, and the like.
16. History of Earth and Sea; of the Shape and Compass of them, and their Configurations compared with each other; and of their broadening or narrowing; of Islands in the Sea; of Gulfs of the Sea, and Salt Lakes within the Land; Isthmuses and Promontories.
17. History of the Motions (if any be) of the Globe of Earth and Sea; and of the Experiments from which such motions may be collected.
18. History of the greater motions and Perturbations in Earth and Sea; Earthquakes, Tremblings and Yawnings of the Earth, Islands newly appearing; Floating Islands; Breakings off of Land by entrance of the Sea, Encroachments and Inundations and contrariwise Recessions of the Sea; Eruptions of Fire from the Earth; Sudden Eruptions of Waters from the Earth; and the like.
19. Natural History of Geography; of Mountains, Vallies, Woods, Plains, Sands, Marshes, Lakes, Rivers, Torrents, Springs, and every variety of their course, and the like; leaving apart Nations, Provinces, Cities, and such like matters pertaining to Civil life.
20. History of Ebbs and Flows of the Sea; Currents, Undulations, and other Motions of the Sea.
21. History of other Accidents of the Sea; its Saltness, its various Colours, its Depth; also of Rocks, Mountains, and Vallies under the Sea, and the like.
22. Next come Histories of the Greater Masses
23. History of Flame and of things Ignited.
24. History of Air, in Substance, not in the Configuration of the World.
25. History of Water, in Substance, not in the Configuration of the World.
26. History of the Earth and the diversity thereof, in Substance, not in the Configuration of the World.
27. Next come Histories of Species
28. History of perfect Metals, Gold, Silver; and of the Mines, Veins, Marcasites of the same; also of the Working in the Mines.
29. History of Quicksilver.
30. History of Fossils; as Vitriol, Sulphur, etc.
31. History of Gems; as the Diamond, the Ruby, etc.
32. History of Stones; as Marble, Touchstone, Flint, etc.
33. History of the Magnet.
34. History of Miscellaneous Bodies, which are neither entirely Fossil nor Vegetable; as Salts, Amber, Ambergris, etc.
35. Chemical History of Metals and Minerals.
36. History of Plants, Trees, Shrubs, Herbs; and of their parts, Roots, Stalks, Wood, Leaves, Flowers, Fruits, Seeds, Gums, etc.
37. Chemical History of Vegetables.
38. History of Fishes, and the Parts and Generation of them.
39. History of Birds, and the Parts and Generation of them.
40. History of Quadrupeds, and the Parts and Generation of them.
41. History of Serpents, Worms, Flies, and other insects; and of the Parts and Generation of them.
42. Chemical History of the things which are taken by Animals.
43. Next come Histories of Man
44. History of the Figure and External Limbs of man, his Stature, Frame, Countenance, and Features; and of the variety of the same according to Races and Climates, or other smaller differences.
45. Physiognomical History of the same.
46. Anatomical History, or of the Internal Members of Man; and of the variety of them, as it is found in the Natural Frame and Structure, and not merely as regards Diseases and Accidents out of the course of Nature.
47. History of the parts of Uniform Structure in Man; as Flesh, Bones, Membranes, etc.
48. History of Humours in Man; Blood, Bile, Seed, etc.
49. History of Excrements; Spittle, Urine, Sweats, Stools, Hair of the Head, Hairs of the Body, Whitlows, Nails, and the like.
50. History of Faculties; Attraction, Digestion, Retention, Expulsion, Sanguification, Assimilation of Aliment into the members, conversion of Blood and Flower of Blood into Spirit, etc.
51. History of Natural and Involuntary Motions; as Motion of the Heart, the Pulses, Sneezing, Lungs, Erection, etc.
52. History of Motions partly Natural and Partly Violent; as of Respiration, Cough, Urine, Stool, etc.
53. History of Voluntary Motions; as of the Instruments of Articulation of Words; Motions of the Eyes, Tongue, Jaws, Hands, Fingers; of Swallowing, etc.
54. History of Sleep and Dreams.
55. History of different habits of Body—Fat, Lean; of the Complexions (as they call them), etc.
56. History of the Generation of Man.
57. History of Conception, Vivification, Gestation in the Womb, Birth, etc.
58. History of the Food of Man; and of all things Eatable and Drinkable; and of all Diet; and of the variety of the same according to nations and smaller differences.
59. History of the Growth and Increase of the Body, in the whole and in its parts.
60. History of the Course of Age; Infancy, Boyhood, Youth, Old Age; of Length and Shortness of Life, and the like, according to nations and lesser differences.
61. History of Life and Death.
62. History Medicinal of Diseases, and of the Symptoms and Signs of them.
63. History Medicinal of the Treatment and Remedies and Cures of Diseases.
64. History Medicinal of those things which preserve the Body and the Health.
65. History Medicinal of those things which relate to the Form and Comeliness of the Body.
66. History Medicinal of those things which alter the Body, and pertain to Alterative Regimen.
67. History of Drugs.
68. History of Surgery.
69. Chemical History of Medicines.
70. History of Vision, and of things Visible.
71. History of Painting, Sculpture, Modelling, etc.
72. History of Hearing and Sound.
73. History of Music.
74. History of Smell and Smells.
75. History of Taste and Tastes.
76. History of Touch, and the objects of Touch.
77. History of Venus, as a species of Touch.
78. History of Bodily Pains, as species of Touch.
79. History of Pleasure and Pain in general.
80. History of the Affections; as Anger, Love, Shame, etc.
81. History of the Intellectual Faculties; Reflexion, Imagination, Discourse, Memory, etc.
82. History of Natural Divinations.
83. History of Diagnostics, or Secret Natural Judgements.
84. History of Cookery, and of the arts thereto belonging, as of the Butcher, Poulterer, etc.
85. History of Baking, and the Making of Bread, and the arts thereto belonging, as of the Miller, etc.
86. History of Wine.
87. History of the Cellar and of different kinds of Drink.
88. History of Sweetmeats and Confections.
89. History of Honey.
90. History of Sugar.
91. History of the Dairy.
92. History of Baths and Ointments.
93. Miscellaneous History concerning the care of the body—as of Barbers, Perfumers, etc.
94. History of the working of Gold, and the arts thereto belonging.
95. History of the manufactures of Wool, and the arts thereto belonging.
96. History of the manufactures of Silk, and the arts thereto belonging.
97. History of the manufactures of Flax, Hemp, Cotton, Hair, and other kinds of Thread, and the arts thereto belonging.
98. History of manufactures of Feathers.
99. History of Weaving, and the arts thereto belonging.
100. History of Dyeing.
101. History of Leather-making, Tanning, and the arts thereto belonging.
102. History of Ticking and Feathers.
103. History of working in Iron.
104. History of Stone-cutting.
105. History of the making of Bricks and Tiles.
106. History of Pottery.
107. History of Cements, etc.
108. History of working in Wood.
109. History of working in Lead.
110. History of Glass and all vitreous substances, and of Glass-making.
111. History of Architecture generally.
112. History of Waggons, Chariots, Litters, etc.
113. History of Printing, of Books, of Writing, of Sealing; of Ink, Pen, Paper, Parchment, etc.
114. History of Wax.
115. History of Basket-making.
116. History of Mat-making, and of manufactures of Straw, Rushes, and the like.
117. History of Washing, Scouring, etc.
118. History of Agriculture, Pasturage, Culture of Woods, etc.
119. History of Gardening.
120. History of Fishing.
121. History of Hunting and Fowling.
122. History of the Art of War, and of the arts thereto belonging, as Armoury, Bow-making, Arrow-making, Musketry, Ordnance, Cross-bows, Machines, etc.
123. History of the Art of Navigation, and of the crafts and arts thereto belonging.
124. History of Athletics and Human Exercises of all kinds.
125. History of Horsemanship.
126. History of Games of all kinds.
127. History of Jugglers and Mountebanks.
128. Miscellaneous History of various Artificial Materials,—Enamel, Porcelain, various cements, etc.
129. History of Salts.
130. Miscellaneous History of various Machines and Motions.
131. Miscellaneous History of Common Experiments which have not grown into an Art.
132. Histories must also be written of Pure Mathematics; though they are rather observations than experiments
133. History of the Natures and Powers of Numbers.
134. History of the Natures and Powers of Figures.

The fragment containing this catalogue (Parasceve—Day of Preparation) was added to Bacon's work on method, The New Logic (Novum Organum), 1620. Besides completing his survey and classification of the sciences (De Augmentis Scientiarum), 1623, he published a few separate writings on topics in the catalogue—Winds, Life and Death, Tides, etc. In 1627, a year after his death, appeared his much misunderstood work, Sylva Sylvarum. He had found that the Latin word sylva meant stuff or raw material, as well as a wood, and called this final work Sylva Sylvarum, which I would translate, "Jungle of Raw Material." He himself referred to it as "an undigested heap of particulars"; yet he was willing it should be published because "he preferred the good of men to anything that might have relation to himself." In it, following his catalogue, he fulfilled the promise made in 1620, of putting nature and the arts to question. Some of the problems suggested for investigation are: congealing of air, turning air into water, the secret nature of flame, motion of gravity, production of cold, nourishing of young creatures in the egg or womb, prolongation of life, the media of sound, infectious diseases, accelerating and preventing putrefaction, accelerating and staying growth, producing fruit without core or seed, production of composts and helps for ground, flying in the air.

In the New Atlantis, a work of imagination, Bacon had represented as already achieved for mankind some of the benefits he wished for: artificial metals, various cements, excellent dyes, animals for vivisection and medical experiment, instruments which generate heat solely by motion, artificial precious stones, conveyance of sound for great distances and in tortuous lines, new explosives. "We imitate," says the guide in the Utopian land, "also flights of birds; we have some degree of flying in the air; we have ships and boats for going under water." Bacon believed in honoring the great discoverers and inventors, and advocated maintaining a calendar of inventions.

He was a fertile and stimulating thinker, and much of his great influence arose from the comprehensiveness that led to his celebrated classification of the sciences.

REFERENCES

Bacon's Philosophical Works, vol. IV, Parasceve, edited by R. L. Ellis, J. Spedding, and D. D. Heath.

Karl Pearson, Grammar of Science.

J. A. Thomson, Introduction to Science.

[CHAPTER VI]

SCIENTIFIC METHOD—GILBERT, GALILEO, HARVEY, DESCARTES

The previous chapter has given some indication of the range of the material which was demanding scientific investigation at the end of the sixteenth and the beginning of the seventeenth century. The same period witnessed a conscious development of the method, or methods, of investigation. As we have seen, Bacon wrote in 1620 a considerable work, The New Logic (Novum Organum), so called to distinguish it from the traditional deductive logic. It aimed to furnish the organ or instrument, to indicate the correct mental procedure, to be employed in the discovery of natural law. Some seventeen years later, the illustrious Frenchman René Descartes (1596-1650) published his Discourse on the Method of rightly conducting the Reason and seeking Truth in the Sciences. Both of these philosophers illustrated by their own investigations the efficiency of the methods which they advocated.

Before 1620, however, the experimental method had already yielded brilliant results in the hands of other scientists. We pass over Leonardo da Vinci and many others in Italy and elsewhere, whose names should be mentioned if we were tracing this method to its origin. By 1600 William Gilbert (1540-1603), physician to Queen Elizabeth, before whom, as a picture in his birthplace illustrates, he was called to demonstrate his discoveries, had published his work on the Magnet, the outcome of about eighteen years of critical research. He may be considered the founder of electrical science. Galileo, who discovered the fundamental principles of dynamics and thus laid the basis of modern physical science, although he did not publish his most important work till 1638, had even before the close of the sixteenth century prepared the way for the announcement of his principles by years of strict experiment. By the year 1616, William Harvey (1578-1657), physician at the court of James I, and, later, of Charles I, had, as the first modern experimental physiologist, gained important results through his study of the circulation of the blood.

It is not without significance that both Gilbert and Harvey had spent years in Italy, where, as we have implied, the experimental method of scientific research was early developed. Harvey was at Padua (1598-1602) within the time of Galileo's popular professoriate, and may well have been inspired by the physicist to explain on dynamical principles the flow of blood through arteries and veins. This conjecture is the more probable, since Galileo, like Harvey and Gilbert, had been trained in the study of medicine. Bacon in turn had in his youth learned something of the experimental method on the Continent of Europe, and, later, was well aware of the studies of Gilbert and Galileo, as well as of Harvey, who was indeed his personal physician.

Although these facts seem to indicate that method may be transmitted in a nation or a profession, or through personal association, there still remains some doubt as to whether anything so intimate as the mental procedure involved in invention and in the discovery of truth can be successfully imparted by instruction. The individuality of the man of genius engaged in investigation must remain a factor difficult to analyze. Bacon, whose purpose was to hasten man's empire over nature through increasing the number of inventions and discoveries, recognized that the method he illustrated is not the sole method of scientific investigation. In fact, he definitely states that the method set forth in the Novum Organum is not original, or perfect, or indispensable. He was aware that his method tended to the ignoring of genius and to the putting of intelligences on one level. He knew that, although it is desirable for the investigator to free his mind from prepossessions, and to avoid premature generalizations, interpretation is the true and natural work of the mind when free from impediments, and that the conjecture of the man of genius must at times anticipate the slow process of painful induction. As we shall see in the nineteenth chapter, the psychology of to-day does not know enough about the workings of the mind to prescribe a fixed mental attitude for the investigator. Nevertheless, Bacon was not wrong in pointing out the virtues of a method which he and many others turned to good account. Let us first glance, however, at the activities of those scientists who preceded Bacon in the employment of the experimental method.

Gilbert relied, in his investigations, on oft-repeated and verifiable experiments, as can be seen from his work De Magnete. He directs the experimenter, for example, to take a piece of loadstone of convenient size and turn it on a lathe to the form of a ball. It then may be called a terrella, or earthkin. Place on it a piece of iron wire. The ends of the wire move round its middle point and suddenly come to a standstill. Mark with chalk the line along which the wire lies still and sticks. Then move the wire to other spots on the terrella and repeat your procedure. The lines thus marked, if produced, will form meridians, all coming together at the poles. Again, place the magnet in a wooden vessel, and then set the vessel afloat in a tub or cistern of still water. The north pole of the stone will seek approximately the direction of the south pole of the earth, etc. It was on the basis of scores of experiments of this sort, carried on from about 1582 till 1600, that Gilbert felt justified in concluding that the terrestrial globe is a magnet. This theory has since that time been abundantly confirmed by navigators. The full title of his book is Concerning the Magnet and Magnetic Bodies, and concerning the Great Magnet the Earth: A New Natural History (Physiologia) demonstrated by many Arguments and Experiments. It does not detract from the credit of Gilbert's result to state that his initial purpose was not to discover the nature of magnetism or electricity, but to determine the true substance of the earth, the innermost constitution of the globe. He was fully conscious of his own method and speaks with scorn of certain writers who, having made no magnetical experiments, constructed ratiocinations on the basis of mere opinions and old-womanishly dreamed the things that were not.

Galileo (1564-1642) even as a child displayed something of the inventor's ingenuity, and when he was nineteen, shortly after the beginning of Gilbert's experiments, his keen perception for the phenomena of motion led to his making a discovery of great scientific moment. He observed a lamp swinging by a long chain in the cathedral of his native city of Pisa, and noticed that, no matter how much the range of the oscillations might vary, their times were constant. He verified his first impressions by counting his pulse, the only available timepiece. Later he invented simple pendulum devices for timing the pulse of patients, and even made some advances in applying his discovery in the construction of pendulum clocks.

In 1589 he was appointed professor of mathematics in the University of Pisa, and within a year or two established through experiment the foundations of the science of dynamics. As early as 1590 he put on record, in a Latin treatise Concerning Motion (De Motu), his dissent from the theories of Aristotle in reference to moving bodies, confuting the Philosopher both by reason and ocular demonstration. Aristotle had held that two moving bodies of the same sort and in the same medium have velocities in proportion to their weights. If a moving body, whose weight is represented by b, be carried through the line c—e which is divided in the point d, if, also, the moving body is divided according to the same proportion as line c—e is in the point d, it is manifest that in the time taken to carry the whole body through c—e, the part will be moved through c—d. Galileo said that it is as clear as daylight that this view is ridiculous, for who would believe that when two lead spheres are dropped from a great height, the one being a hundred times heavier than the other, if the larger took an hour to reach the earth, the smaller would take a hundred hours? Or, that if from a high tower two stones, one twice the weight of the other, should be pushed out at the same moment, the larger would strike the ground while the smaller was still midway? His biography tells that Galileo in the presence of professors and students dropped bodies of different weights from the height of the Leaning Tower of Pisa to demonstrate the truth of his views. If allowance be made for the friction of the air, all bodies fall from the same height in equal times: the final velocities are proportional to the times; the spaces passed through are proportional to the squares of the times. The experimental basis of the last two statements was furnished by means of an inclined plane, down a smooth groove in which a bronze ball was allowed to pass, the time being ascertained by means of an improvised water-clock.

Galileo's mature views on dynamics received expression in a work published in 1638, Mathematical Discourses and Demonstrations concerning Two New Sciences relating to Mechanics and Local Movements. It treats of cohesion and resistance to fracture (strength of materials), and uniform, accelerated, and projectile motion (dynamics). The discussion is in conversation form. The opening sentence shows Galileo's tendency to base theory on the empirical. It might be freely translated thus: "Large scope for intellectual speculation, I should think, would be afforded, gentlemen, by frequent visits to your famous Venetian Dockyard (arsenale), especially that part where mechanics are in demand; seeing that there every sort of instrument and machine is put to use by numbers of workmen, among whom, taught both by tradition and their own observation, there must be some very skillful and also able to talk." The view of the shipbuilders, that a large galley before being set afloat is in greater danger of breaking under its own weight than a small galley, is the starting-point of this most important of Galileo's contributions to science.

Vesalius (1514-1564) had in his work on the structure of the human body (De Humani Corporis Fabrica, 1543) shaken the authority of Galen's anatomy; it remained for Harvey on the basis of the new anatomy to improve upon the Greek physician's experimental physiology. Harvey professed to learn and teach anatomy, not from books, but from dissections, not from the dogmas of the philosophers, but from the fabric of nature.

There have come down to us notes of his lectures on anatomy delivered first in 1616. A brief extract will show that even at that date he had already formulated a theory of the circulation of the blood:—

"

[1] By the structure of the heart it appears that the blood is continually transfused through the lungs to the aorta—as by the two clacks of a water-ram for raising water.

"It is shown by ligature that there is continuous motion of the blood from arteries to veins.

"Whence Δ it is demonstrated that there is a continuous motion of the blood in a circle, affected by the beat of the heart."

It was not till 1628 that Harvey published his Anatomical Disquisition on the Motion of the Heart and Blood in Animals. It gives the experimental basis of his conclusions. If a live snake be laid open, the heart will be seen pulsating and propelling its contents. Compress the large vein entering the heart, and the part intervening between the point of constriction and the heart becomes empty and the organ pales and shrinks. Remove the pressure, and the size and color of the heart are restored. Now compress the artery leading from the organ, and the part between the heart and the point of pressure, and the heart itself, become distended and take on a deep purple color. The course of the blood is evidently from the vena cava through the heart to the aorta. Harvey in his investigations made use of many species of animals—at least eighty-seven.

It was believed by some, before Harvey's demonstrations, that the arteries were hollow pipes carrying air from the lungs throughout the body, although Galen had shown by cutting a dog's trachea, inflating the lungs and tying the trachea, that the lungs were in an enclosing sack which retained the air. Harvey, following Galen, held that the pulmonary artery, carrying blood to the lungs from the right side of the heart, and the pulmonary veins, carrying blood from the lungs to the left side of the heart, intercommunicate in the hidden porosities of the lungs and through minute inosculations.

In man the vena cava carries the blood to the right side of the heart, the pulmonary artery inosculates with the pulmonary veins, which convey it to the left side of the heart. This muscular pump drives it into the aorta. It still remains to be shown that in the limbs the blood passes from the arteries to the veins. Bandage the arm so tightly that no pulse is felt at the wrist. The hand appears at first natural, and then grows cold. Loose the bandage sufficiently to restore the pulse. The hand and forearm become suffused and swollen. In the first place the supply of blood from the deep-lying arteries is cut off. In the second case the blood returning by the superficial veins is dammed back. In the limbs as in the lungs the blood passes from artery to vein by anastomoses and porosities. All these arteries have their source in the aorta; all these veins pour their stream ultimately into the vena cava. The veins have valves, which prevent the blood flowing except toward the heart. Again, the veins and arteries form a connected system; for through either a vein or an artery all the blood may be drained off. The arguments by which Harvey supported his view were various. The opening clause of his first chapter, "When I first gave my mind to vivisection as a means of discovering the motions and uses of the heart," throws a strong light on his special method of experimental investigation.

Bacon, stimulated by what he called philanthropia, always aimed, as we have seen, to establish man's control over nature. But all power of a high order depends on an understanding of the essential character, or law, of heat, light, sound, gravity, and the like. Nothing short of a knowledge of the underlying nature of phenomena can give science advantage over chance in hitting upon useful discoveries and inventions. It is, therefore, natural to find him applying his method of induction—his special method of true induction—to the investigation of heat.

In the first place, let there be mustered, without premature speculation, all the instances in which heat is manifested—flame, lightning, sun's rays, quicklime sprinkled with water, damp hay, animal heat, hot liquids, bodies subjected to friction. Add to these, instances in which heat seems to be absent, as moon's rays, sun's rays on mountains, oblique rays in the polar circle. Try the experiment of concentrating on a thermoscope, by means of a burning-glass, the moon's rays. Try with the burning-glass to concentrate heat from hot iron, from common flame, from boiling water. Try a concave glass with the sun's rays to see whether a diminution of heat results. Then make record of other instances, in which heat is found in varying degrees. For example, an anvil grows hot under the hammer. A thin plate of metal under continuous blows might grow red like ignited iron. Let this be tried as an experiment.

After the presentation of these instances induction itself must be set to work to find out what factor is ever present in the positive instances, what factor is ever wanting in the negative instances, what factor always varies in the instances which show variation. According to Bacon it is in the process of exclusion that the foundations of true induction are laid. We can be certain, for example, that the essential nature of heat does not consist in light and brightness, since it is present in boiling water and absent in the moon's rays.

The induction, however, is not complete till something positive is established. At this point in the investigation it is permissible to venture an hypothesis in reference to the essential character of heat. From a survey of the instances, all and each, it appears that the nature of which heat is a particular case is motion. This is suggested by flame, simmering liquids, the excitement of heat by motion, the extinction of fire by compression, etc. Motion is the genus of which heat is the species. Heat itself, its essence, is motion and nothing else.

It remains to establish its specific differences. This accomplished, we arrive at the definition: Heat is a motion, expansive, restrained, and acting in its strife upon the smaller particles of bodies. Bacon, glancing toward the application of this discovery, adds: "If in any natural body you can excite a dilating or expanding motion, and can so repress this motion and turn it back upon itself, that the dilation shall not proceed equally, but have its way in one part and be counteracted in another, you will undoubtedly generate heat." The reader will recall that Bacon looked for the invention of instruments that would generate heat solely by motion.

Descartes was a philosopher and mathematician. In his Discourse on Method and his Rules for the Direction of the Mind (1628) he laid emphasis on deduction rather than on induction. In the subordination of particulars to general principles he experienced a satisfaction akin to the sense of beauty or the joy of artistic production. He speaks enthusiastically of that pleasure which one feels in truth, and which in this world is about the only pure and unmixed happiness.

At the same time he shared Bacon's distrust of the Aristotelian logic and maintained that ordinary dialectic is valueless for those who desire to investigate the truth of things. There is need of a method for finding out the truth. He compares himself to a smith forced to begin at the beginning by fashioning tools with which to work.

In his method of discovery he determined to accept nothing as true that he did not clearly recognize to be so. He stood against assumptions, and insisted on rigid proof. Trust only what is completely known. Attain a certitude equal to that of arithmetic and geometry. This attitude of strict criticism is characteristic of the scientific mind.

Again, Descartes was bent on analyzing each difficulty in order to solve it; to neglect no intermediate steps in the deduction, but to make the enumeration of details adequate and methodical. Preserve a certain order; do not attempt to jump from the ground to the gable, but rise gradually from what is simple and easily understood.

Descartes' interest was not in the several branches of mathematics; rather he wished to establish a universal mathematics, a general science relating to order and measurement. He considered all physical nature, including the human body, as a mechanism, capable of explanation on mathematical principles. But his immediate interest lay in numerical relationships and geometrical proportions.

Recognizing that the understanding was dependent on the other powers of the mind, Descartes resorted in his mathematical demonstrations to the use of lines, because he could find no method, as he says, more simple or more capable of appealing to the imagination and senses. He considered, however, that in order to bear the relationships in memory or to embrace several at once, it was essential to explain them by certain formulæ, the shorter the better. And for this purpose it was requisite to borrow all that was best in geometrical analysis and algebra, and to correct the errors of one by the other.

Descartes was above all a mathematician, and as such he may be regarded as a forerunner of Newton and other scientists; at the same time he developed an exact scientific method, which he believed applicable to all departments of human thought. "Those long chains of reasoning," he says, "quite simple and easy, which geometers are wont to employ in the accomplishment of their most difficult demonstrations, led me to think that everything which might fall under the cognizance of the human mind might be connected together in the same manner, and that, provided only one should take care not to receive anything as true which was not so, and if one were always careful to preserve the order necessary for deducing one truth from another, there would be none so remote at which he might not at last arrive, or so concealed which he might not discover."

REFERENCES

Francis Bacon, Philosophical Works (Ellis and Spedding edition), vol. IV, Novum Organum.

J. J. Fahie, Galileo; His Life and Work.

Galileo, Two New Sciences; translated by Henry Crew and Alphonse De Salvio.

William Gilbert, On the Loadstone; translated by P. F. Mottelay.

William Harvey, An Anatomical Disquisition on the Motion of the Heart and Blood in Animals.

T. H. Huxley, Method and Results.

D'Arcy Power, William Harvey (in Masters of Medicine).

FOOTNOTES:

[1] This is Harvey's monogram, which he used in his notes to mark any original observation.

[CHAPTER VII]

SCIENCE AS MEASUREMENT—TYCHO BRAHE, KEPLER, BOYLE

Considering the value for clearness of thought of counting, measuring and weighing, it is not surprising to find that in the seventeenth century, and even at the end of the sixteenth, the advance of the sciences was accompanied by increased exactness of measurement and by the invention of instruments of precision. The improvement of the simple microscope, the invention of the compound microscope, of the telescope, the micrometer, the barometer, the thermoscope, the thermometer, the pendulum clock, the improvement of the mural quadrant, sextant, spheres, astrolabes, belong to this period.

Measuring is a sort of counting, and weighing a form of measuring. We may count disparate things whether like or unlike. When we measure or weigh we apply a standard and count the times that the unit—cubit, pound, hour—is found to repeat itself. We apply our measure to uniform extension, meting out the waters by fathoms or space by the sun's diameter, and even subject time to arbitrary divisions. The human mind has been developed through contact with the multiplicity of physical objects, and we find it impossible to think clearly and scientifically about our environment without dividing, weighing, measuring, counting.

In measuring time we cannot rely on our inward impressions; we even criticize these impressions and speak of time as going slowly or quickly. We are compelled in the interests of accuracy to provide an objective standard in the clock, or the revolving earth, or some other measurable thing. Similarly with weight and heat; we cannot rely on the subjective impression, but must devise apparatus to record by a measurable movement the amount of the pressure or the degree of temperature.

"God ordered all things by measure, number, and weight." The scientific mind does not rest satisfied till it is able to see phenomena in their number relationships. Scientific thought is in this sense Pythagorean, that it inquires in reference to quantity and proportion.

As implied in a previous chapter, number relations are not clearly grasped by primitive races. Many primitive languages have no words for numerals higher than five. That fact does not imply that these races do not know the difference between large and small numbers, but precision grows with civilization, with commercial pursuits, and other activities, such as the practice of medicine, to which the use of weights and measures is essential. Scientific accuracy is dependent on words and other means of numerical expression. From the use of fingers and toes, a rude score or tally, knots on a string, or a simple abacus, the race advances to greater refinement of numerical expression and the employment of more and more accurate apparatus.

One of the greatest contributors to this advance was the celebrated Danish astronomer, Tycho Brahe (1546-1601). Before 1597 he had completed his great mural quadrant at the observatory of Uraniborg. He called it with characteristic vanity the Tichonic quadrant. It consisted of a graduated arc of solid polished brass five inches broad, two inches thick, and with a radius of about six and three quarters feet. Each degree was divided into minutes, and each minute into six parts. Each of these parts was then subdivided into ten seconds, which were indicated by dots arranged in transverse oblique lines on the width of brass.

The arc was attached in the observation room to a wall running exactly north, and so secured with screws (firmissimis cochleis) that no force could move it. With its concavity toward the southern sky it was closely comparable, though reverse, to the celestial meridian throughout its length from horizon to zenith. The south wall, above the point where the radii of the quadrant met, was pierced by a cylinder of gilded brass placed in a rectangular opening, which could be opened or closed from the outside. The observation was made through one of two sights that were attached to the graduated arc and could be moved from point to point on it. In the sights were parallel slits, right, left, upper, lower. If the altitude and the transit through the meridian were to be taken at the same time the four directions were to be followed. It was the practice for the student making the observation to read off the number of degrees, minutes, etc., of the angle at which the altitude or transit was observed, so that it might be recorded by a second student. A third took the time from two clock dials when the observer gave the signal, and the exact moment of observation was also recorded by student number two. The clocks recorded minutes and the smaller divisions of time; great care, however, was required to obtain good results from them. There were four clocks in the observatory, of which the largest had three wheels, one wheel of pure solid brass having twelve hundred teeth and a diameter of two cubits.

Lest any space on the wall should lie empty a number of paintings were added: Tycho himself in an easy attitude seated at a table and directing from a book the work of his students. Over his head is an automatic celestial globe invented by Tycho and constructed at his own expense in 1590. Over the globe is a part of Tycho's library. On either side are represented as hanging small pictures of Tycho's patron, Frederick II of Denmark (d. 1588) and Queen Sophia. Then other instruments and rooms of the observatory are pictured; Tycho's students, of whom there were always at least six or eight, not to mention younger pupils. There appears also his great brass globe six feet in diameter. Then there is pictured Tycho's chemical laboratory, on which he has expended much money. Finally comes one of Tycho's hunting dogs—very faithful and sagacious; he serves here as a hieroglyph of his master's nobility as well as of sagacity and fidelity. The expert architect and the two artists who assisted Tycho are delineated in the landscape and even in the setting sun in the top-most part of the painting, and in the decoration above.

The principal use of this largest quadrant was the determination of the angle of elevation of the stars within the sixth part of a minute, the collineation being made by means of one of the sights, the parallel horizontal slits in which were aligned with the corresponding parts of the circumference of the cylinder. The altitude was recorded according to the position of the sight attached to the graduated arc.

Tycho Brahe had a great reverence for Copernicus, but he did not accept his planetary system; and he felt that advance in astronomy depended on painstaking observation. For over twenty years under the kings of Denmark he had good opportunities for pursuing his investigation. The island of Hven became his property. A thoroughly equipped observatory was provided, including printing-press and workshops for the construction of apparatus. As already implied, capable assistants were at the astronomer's command. In 1598, after having left Denmark, Tycho in a splendid illustrated book (Astronomiæ Instauratæ Mechanica) gave an account of this astronomical paradise on the Insula Venusia as he at times called it. The book, prepared for the hands of princes, contains about twenty full-page colored illustrations of astronomical instruments (including, of course, the mural quadrant), of the exterior of the observatory of Uraniborg, etc. The author had a consciousness of his own worth, and deserves the name Tycho the Magnificent. The results that he obtained were not unworthy of the apparatus employed in his observations, and before he died at Prague in 1601, Tycho Brahe had consigned to the worthiest hands the painstaking record of his labors.

Johann Kepler (1571-1630) had been called, as the astronomer's assistant, to the Bohemian capital in 1600 and in a few months fell heir to Tycho's data in reference to 777 stars, which he made the basis of the Rudolphine tables of 1627. Kepler's genius was complementary to that of his predecessor. He was gifted with an imagination to turn observations to account. His astronomy did not rest in mere description, but sought the physical explanation. He had the artist's feeling for the beauty and harmony, which he divined before he demonstrated, in the number relations of the planetary movements. After special studies of Mars based on Tycho's data, he set forth in 1609 (Astronomia Nova) (1) that every planet moves in an ellipse of which the sun occupies one focus, and (2) that the area swept by the radius vector from the planet to the sun is proportional to the time. Luckily for the success of his investigation the planet on which he had concentrated his attention is the one of all the planets then known, the orbit of which most widely differs from a circle. In a later work (Harmonica Mundi, 1619) the title of which, the Harmonics of the Universe, proclaimed his inclination to Pythagorean views, he demonstrated (3) that the square of the periodic time of any planet is proportional to the cube of its mean distance from the sun.

Kepler's studies were facilitated by the invention, in 1614 by John Napier, of logarithms, which have been said, by abridging tedious calculations, to double the life of an astronomer. About the same time Kepler in purchasing some wine was struck by the rough-and-ready method used by the merchant to determine the capacity of the wine-vessels. He applied himself for a few days to the problems of mensuration involved, and in 1615 published his treatise (Stereometria Doliorum) on the cubical contents of casks (or wine-jars), a source of inspiration to all later writers on the accurate determination of the volume of solids. He helped other scientists and was himself richly helped. As early as 1610 there had been presented to him a means of precision of the first importance to the progress of astronomy, namely, a Galilean telescope.

The early history of telescopes shows that the effect of combining two lenses was understood by scientists long before any particular use was made of this knowledge; and that those who are accredited with introducing perspective glasses to the public hit by accident upon the invention. Priority was claimed by two firms of spectacle-makers in Middelburg, Holland, namely, Zacharias, miscalled Jansen, and Lippershey. Galileo heard of the contrivance in July, 1609, and soon furnished so powerful an instrument of discovery that things seen through it appeared more than thirty times nearer and almost a thousand times larger than when seen by the naked eye. He was able to make out the mountains in the moon, the satellites of Jupiter in rotation, the spots on the revolving sun; but his telescope afforded only an imperfect view of Saturn. Of course these facts, published in 1610 (Sidereus Nuncius), strengthened his advocacy of the Copernican system. Galileo laughingly wrote Kepler that the professors of philosophy were afraid to look through his telescope lest they should fall into heresy. The German astronomer, who had years before written on the optics of astronomy, now (1611) produced his Dioptrice, the first satisfactory statement of the theory of the telescope.

About 1639 Gascoigne, a young Englishman, invented the micrometer, which enables an observer to adjust a telescope with very great precision. Before the invention of the micrometer exactitude was impossible, because the adjustment of the instrument depended on the discrimination of the naked eye. The micrometer was a further advance in exact measurement. Gascoigne's determinations of, for example, the diameter of the sun, bear comparison with the findings of even recent astronomical science.

The history of the microscope is closely connected with that of the telescope. In the first half of the seventeenth century the simple microscope came into use. It was developed from the convex lens, which, as we have seen in a previous chapter, had been known for centuries, if not from remote antiquity. With the simple microscope Leeuwenhoek before 1673 had studied the structure of minute animal organisms and ten years later had even obtained sight of bacteria. Very early in the same century Zacharias had presented Prince Maurice, the commander of the Dutch forces, and the Archduke Albert, governor of Holland, with compound microscopes. Kircher (1601-1680) made use of an instrument that represented microscopic forms as one thousand times larger than their actual size, and by means of the compound microscope Malpighi was able in 1661 to see blood flowing from the minute arteries to the minute veins on the lung and on the distended bladder of the live frog. The Italian microscopist thus, among his many achievements, verified by observation what Harvey in 1628 had argued must take place.

In this same epoch apparatus of precision developed in other fields. Weight clocks had been in use as time-measurers since the thirteenth century, but they were, as we have seen, difficult to control and otherwise unreliable. Even in the seventeenth century scientists in their experiments preferred some form of water-clock. In 1636 Galileo, in a letter, mentioned the feasibility of constructing a pendulum clock, and in 1641 he dictated a description of the projected apparatus to his son Vincenzo and to his disciple Viviani. He himself was then blind, and he died the following year. His instructions were never carried into effect. However, in 1657 Christian Huygens applied the pendulum to weight clocks of the old stamp. In 1674 he gave directions for the manufacture of a watch, the movement of which was driven by a spring.

Galileo, to whom the advance in exact science is so largely indebted, must also be credited with the first apparatus for the measurement of temperatures. This was invented before 1603 and consisted of a glass bulb with a long stem of the thickness of a straw. The bulb was first heated and the stem placed in water. The point at which the water, which rose in the tube, might stand was an indication of the temperature. In 1631 Jean Rey just inverted this contrivance, filling the bulb with water. Of course these thermoscopes would register the effect of varying pressures as well as temperatures, and they soon made way for the thermometer and the barometer. Before 1641 a true thermometer was constructed by sealing the top of the tube after driving out the air by heat. Spirits of wine were used in place of water. Mercury was not employed till 1670.

Descartes and Galileo had brought under criticism the ancient idea that nature abhors a vacuum. They knew that the horror vacui was not sufficient to raise water in a pump more than about thirty-three feet. They had also known that air has weight, a fact which soon served to explain the so-called force of suction. Galileo's associate Torricelli reasoned that if the pressure of the air was sufficient to support a column of water thirty-three feet in height, it would support a column of mercury of equal weight. Accordingly in 1643 he made the experiment of filling with mercury a glass tube four feet long closed at the upper end, and then opening the lower end in a basin of mercury. The mercury in the tube sank until its level was about thirty inches above that of the mercury in the basin, leaving a vacuum in the upper part of the tube. As the specific gravity of mercury is 13, Torricelli knew that his supposition had been correct and that the column of mercury in the tube and the column of water in the pump were owing to the pressure or weight of the air.

Pascal thought that this pressure would be less at a high altitude. His supposition was tested on a church steeple at Paris, and, later, on the Puy de Dôme, a mountain in Auvergne. In the latter case a difference of three inches in the column of mercury was shown at the summit and base of the ascent. Later Pascal experimented with the siphon and succeeded in explaining it on the principle of atmospheric pressure.

Torricelli in the space at the top of his barometer (pressure-gauge) had produced what is called a Torricellian vacuum. Otto von Guericke, a burgomaster of Magdeburg, who had traveled in France and Italy, succeeded in constructing an air-pump by means of which air might be exhausted from a vessel. Some of his results became widely known in 1657, though his works were not published till 1673.

Robert Boyle (1626-1691), born at Castle Lismore in Ireland, was the seventh son and fourteenth child of the distinguished first Earl of Cork. He was early acquainted with these various experiments in reference to the air, as well as with Descartes' theory that air is nothing but a congeries or heap of small, and, for the most part, flexible particles. In 1659 he wrote his New Experiments Physico-Mechanical touching the Spring of the Air. Instead of spring, he at times used the word elater (ἐλατὴρ). In this treatise he describes experiments with the improved air-pump constructed at his suggestion by his assistant, Robert Hooke.

One of Boyle's critics, a professor at Louvain, while admitting that air had weight and elasticity, denied that these were sufficient to account for the results ascribed to them. Boyle thereupon published a Defence of the Doctrine touching the Spring and Weight of the Air. He felt able to prove that the elasticity of the air could under circumstances do far more than sustain twenty-nine or thirty inches of mercury. In support of his view he cited a recent experiment.

He had taken a piece of strong glass tubing fully twelve feet in length. (The experiment was made by a well-lighted staircase, the tube being suspended by strings.) The glass was heated more than a foot from the lower end, and bent so that the shorter leg of twelve inches was parallel with the longer. The former was hermetically sealed at the top and marked off in forty-eight quarter-inch spaces. Into the opening of the longer leg, also graduated, mercury was poured. At first only enough was introduced to fill the arch, or bent part of the tube below the graduated legs. The tube was then inclined so that the air might pass from one leg to the other, and equality of pressure at the start be assured. Then more mercury was introduced and every time that the air in the shorter leg was compressed a half or a quarter of an inch, a record was made of the height of the mercury in the long leg of the tube. Boyle reasoned that the compressed air was sustaining the pressure of the column of mercury in the long leg plus the pressure of the atmosphere at the tube's opening, equivalent to 29²⁄₁₆ inches of mercury. Some of the results were as follows: When the air in the short tube was compressed from 12 to 3 inches, it was under a pressure of 117⁹⁄₁₆ inches of mercury; when compressed to 4 it was under pressure of 87¹⁵⁄₁₆ inches of mercury; when compressed to 6, 58¹³⁄₁₆; to 9, 39⁵⁄₈. Of course, when at the beginning of the experiment there were 12 inches of air in the short tube, it was under the pressure of the atmosphere, equal to that of 29²⁄₁₆ inches of mercury. Boyle with characteristic caution was not inclined to draw too general a conclusion from his experiment. However, it was evident, making allowance for some slight irregularity in the experimental results, that air reduced under pressure to one half its original volume, doubles its resistance; and that if it is further reduced to one half,—for example, from six to three inches,—it has four times the resistance of common air. In fact, Boyle had sustained the hypothesis that supposes the pressures and expansions to be in reciprocal proportions.

REFERENCES

Sir Robert S. Ball, Great Astronomers.

Robert Boyle, Works (edited by Thomas Birch).

Sir David Brewster, Martyrs of Science.

J. L. E. Dreyer, Tycho Brahe.

Sir Oliver Lodge, Pioneers of Science.

Flora Masson, Robert Boyle; a Biography.

[CHAPTER VIII]

COÖPERATION IN SCIENCE—THE ROYAL SOCIETY

The period from 1637 to 1687 affords a good illustration of the value for the progress of science of the coöperation in the pursuit of truth of men of different creeds, nationalities, vocations, and social ranks. At, or even before, the beginning of that period the need of coöperation was indicated by the activities of two men of pronouncedly social temperament and interests, namely, the French Minim father, Mersenne, and the Protestant Prussian merchant, Samuel Hartlib.

Mersenne was a stimulating and indefatigable correspondent. His letters to Galileo, Jean Rey, Hobbes, Descartes, Gassendi, not to mention other scientists and philosophers, constitute an encyclopedia of the learning of the time. A mathematician and experimenter himself, he had a genius for eliciting discussion and research by means of adroit questions. Through him Descartes was drawn into debate with Hobbes, and with Gassendi, a champion of the experimental method. Through him the discoveries of Harvey, Galileo, and Torricelli, as well as of many others, became widely known. His letters, in the dearth of scientific associations and the absence of scientific periodicals, served as a general news agency among the learned of his time. It is not surprising that a coterie gathered about him at Paris. Hobbes spent months in daily intercourse with this group of scientists in the winter of 1636-37.

Hartlib, though he scarcely takes rank with Mersenne as a scientist, was no less influential. Of a generous and philanthropic disposition, he repeatedly impoverished himself in the cause of human betterment. His chief reliance was on education and improved methods of husbandry, but he resembled Horace Greeley in his hospitality to any project for the public welfare.

One of Hartlib's chief hopes for the regeneration of England, if not of the whole world, rested on the teachings of the educational reformer Comenius, a bishop of the Moravian Brethren. In 1637, Comenius having shown himself rather reluctant to put his most cherished plans before the public, his zealous disciple precipitated matters, and on his own responsibility, and unknown to Comenius, issued from his library at Oxford Preludes to the Endeavors of Comenius. Besides Hartlib's preface it contained a treatise by the great educator on a Seminary of Christian Pansophy, a method of imparting an encyclopedic knowledge of the sciences and arts.

The two friends were followers of the Baconian philosophy. They were influenced, as many others of the time, by the New Atlantis, which went through ten editions between 1627 and 1670, and which outlined a plan for an endowed college with thirty-six Fellows divided into groups—what would be called to-day a university of research endowed by the State. It is not surprising to find Comenius (who in his student days had been under the influence of Alsted, author of an encyclopedia on Baconian lines) speaking in 1638 on the need of a collegiate society for carrying on the educational work that he himself had at heart.

In 1641 Hartlib published a work of fiction in the manner of the New Atlantis, and dedicated it to the Long Parliament. In the same year he urged Comenius to come to London, and published another work, A Reformation of Schools. He had great influence and did not hesitate to use it in his adoptive country. Everybody knew Hartlib, and he was acquainted with all the strata of English society; for although his father had been a merchant, first in Poland and later in Elbing, his mother was the daughter of the Deputy of the English Company in Dantzic and had relatives of rank in London, where Hartlib spent most of his life. He gained the good-will of the Puritan Government, and even after Cromwell's death was working, in conjunction with Boyle, for the establishment of a national council of universal learning with Wilkins as president.

When Comenius arrived in London he learned that the invitation had been sent by order of Parliament. This body was very anxious to take up the question of education, especially university education. Bacon's criticisms of Oxford and Cambridge were still borne in mind; the legislators considered that the college curriculum was in need of reformation, that there ought to be more fraternity and correspondence among the universities of Europe, and they even contemplated the endowment by the State of scientific experiment. They spoke of erecting a university at London, where Gresham College had been established in 1597 and Chelsea College in 1610. It was proposed to place Gresham College, the Savoy, or Winchester College, at the disposition of the pansophists. Comenius thought that nothing was more certain than that the design of the great Verulam concerning the opening somewhere of a universal college, devoted to the advancement of the sciences, could be carried out. The impending struggle, however, between Charles I and the Parliament prevented the attempt to realize the pansophic dream, and the Austrian Slav, who knew something of the horrors of civil war, withdrew, discouraged, to the Continent.

Nevertheless, Hartlib did not abandon the cause, but in 1644 broached Milton on the subject of educational reform, and drew from him the brief but influential tract on Education. In this its author alludes rather slightingly to Comenius, who had something of Bacon's infelicity in choice of titles and epithets and who must have seemed outlandish to the author of Lycidas and Comus. But Milton joined in the criticism of the universities—the study of words rather than things—and advocated an encyclopedic education based on the Greek and Latin writers of a practical and scientific tendency (Aristotle, Theophrastus, Cato, Varro, Vitruvius, Seneca, and others). He outlined a plan for the establishment of an institution to be known by the classical (and Shakespearian) name "Academy"—a plan destined to have a great effect on education in the direction indicated by the friends of pansophia.

In this same year Robert Boyle, then an eager student of eighteen just returned to England from residence abroad, came under the influence of the genial Hartlib. In 1646 he writes his tutor inquiring about books on methods of husbandry and referring to the new philosophical college, which valued no knowledge but as it had a tendency to use. A few months later he was in correspondence with Hartlib in reference to the Invisible College, and had written a third friend that the corner-stones of the invisible, or, as they termed themselves, the philosophical college, did now and then honor him with their company. These philosophers whom Boyle entertained, and whose scientific acumen, breadth of mind, humility, and universal good-will he found so congenial, were the nucleus of the Royal Society of London, of which, on its definite organization in 1662, he was the foremost member. They had begun to meet together in London about 1645, worthy persons inquisitive into natural philosophy—Wilkins, interested in the navigation of the air and of waters below the surface; Wallis, mathematician and grammarian; the many-sided Petty, political economist, and inventor of a double-bottomed boat, who had as a youth of twenty studied with Hobbes in Paris in 1643, and in 1648 was to write his first treatise on industrial education at the suggestion of Hartlib, and finally make a survey of Ireland and acquire large estates; Foster, professor of astronomy at Gresham College; Theodore Haak from the Pfalz; a number of medical men, Dr. Merret, Dr. Ent, a friend of Harvey, Dr. Goddard, who could always be relied upon to undertake an experiment, Dr. Glisson, the physiologist, author in 1654 of a treatise on the liver (De Hepate), and others. They met once a week at Goddard's in Wood Street, at the Bull's Head Tavern in Cheapside, and at Gresham College.

Dr. Wilkins, the brother-in-law of Cromwell, who is regarded by some as the founder of the Royal Society, removed to Oxford, as Warden of Wadham, in 1649. Here he held meetings and conducted experiments in conjunction with Wallis, Goddard, Petty, Boyle, and others, including Ward (afterwards Bishop of Salisbury) interested in Bulliau's Astronomy; and the celebrated physician and anatomist, Thomas Willis, author of a work on the brain (Cerebri Anatome), and another on fevers (De Febribus), in which he described epidemic typhoid as it occurred during the Civil War in 1643.