AËRIAL NAVIGATION

A POPULAR TREATISE
ON THE GROWTH OF AIR CRAFT AND
ON AËRONAUTICAL METEOROLOGY

BY

Albert Francis Zahm, A.M., M.E., Ph.D.

SECRETARY OF THE AËRO CLUB OF WASHINGTON; GOVERNOR OF THE AËRO CLUB
OF AMERICA; GENERAL SECRETARY OF THE INTERNATIONAL CONFERENCES
ON AËRIAL NAVIGATION IN 1893 AND 1907; OFFICIAL AMERICAN
DELEGATE TO THE AËRONAUTIC CONGRESS OF 1900; FORMERLY
LECTURER ON MECHANICS IN THE UNITED STATES BUREAU
OF STANDARDS, AND PROFESSOR OF MECHANICS
IN THE CATHOLIC UNIVERSITY
OF AMERICA

NEW YORK AND LONDON
D. APPLETON AND COMPANY
1911

Copyright, 1911, by
D. APPLETON AND COMPANY

Published September, 1911

Printed in the United States of America

PREFACE

The purpose of this work is to portray in popular terms the substantial progress of aëronautics from its earliest beginning to the present time. Beyond the introductory account, little note is taken of experiments, however picturesque or clever, which constitute no advance in the art, or lead to no useful result. At times some minutiæ are presented to complete the story of an important series of achievements; but the unproductive efforts of impractical zealots, however prominent or widely known in their day, receive scant, if any, attention. Failures and tragedies where introduced, are described for the lessons involved rather than for any curious interest investing them. The griefs and grotesque follies of aëronautic imbeciles form a long story, but a futile and unprofitable one, of slight concern in the evolutionary history of a veritable science.

A general history of aërial locomotion would naturally be divided into four parts, treating respectively of passive balloons, power balloons, passive flyers, and power flyers; but in this work a separate treatment has not been allotted to passive flyers because of their too backward state of development. Passive gliders which maneuver in the air merely by virtue of gravitational force, or acquired momentum, are familiar enough; but the much more interesting passive flyers of human construction, adapted to rise without motive power considerably beyond their initial level, or to soar far aloft, and sail long distances by virtue of favorable winds, are still in their infancy. It may be hoped, however, that the vulture’s art which now is well nigh overlooked, because of the triumphant advance of dynamic flight, will soon receive such attention that future treatises may relate human achievements in soaring that shall rival the dexterous and marvelous feats of the condor and albatross, even as the majestic sweep of the dynamic aëroplane now rivals the powerful rowing flight of the strongest birds of prey.

Following the story of the evolution of air ships, a brief account of the medium they navigate has been added. In particular, the circumstances which affect the density and motion of the air have been studied; for the density of the air determines the static lift of air ships; the density and speed of impact of the air together determine the dynamic lift and the resistance to progression; while the velocity of the air current conditions the possible speed of travel in any direction. It is important, therefore, that the aëronautical student should have some acquaintance with the general properties of the air which affect its density, and some knowledge of the generation and prevalence both of the great currents of the atmosphere, and of the local winds and invisible turmoils which so nearly concern the safety and effective progress of the aërial navigator.

The French units of measurement have been freely used, as well as the English. This seems advisable because the official rules and records of international aëronautic events are partly expressed in the metric system. Moreover, the navigation of a universal medium seems to call for such universal standards. Indeed a peculiar mission of world travel is to eliminate provincialism, and to promote universalism of thought, of sentiment, and of custom.

In order to lighten the book for the popular reader, some interesting historical facts and much important quantitative data are placed in the Appendices, where they may be available to the technical or special student.

It is a pleasant duty to acknowledge here my obligations to the U. S. Signal Corps, the Smithsonian Institution, and the U. S. Weather Bureau, for much assistance in collecting the materials for this work. Dr. W. J. Humphreys, of the U. S. Weather Bureau, has very kindly read the manuscript for the chapters on the atmosphere.

My thanks are due also to the Scientific American and to Aëronautics for the use of photographs for the illustrations, as also to the manufacturers of various aircraft, and to Mr. W. J. Hammer, Mr. Carl Dientsbach, and Mr. A. S. Levino.

A. F. Zahm.

Cosmos Club
Washington, D. C.,
January, 1911.

CONTENTS

LIST OF PLATES

LIST OF ILLUSTRATIONS IN TEXT

INTRODUCTION

INTRODUCTION

Of silver wings he took a shining pair,

Fringed with gold, unwearied, nimble, swift;

With these he parts the winds, the clouds, the air,

And over seas and earth himself doth lift.

Thus clad he cuts the spheres and circles fair,

And the pure skies with sacred feathers clift;

On Lebanon at first his feet he set

And shook his wings with rosy may-dews wet.

Tasso, Canto I, XIV.

How beautiful! May we hope ever to journey thus, on wings actuated by human power? It is an old question, once dear to the philosopher and fool alike, but now important mainly to the fool. Or say more kindly it is the affair of untechnical inventors—the amateur, the rustic, the man of chimerical dreams. For the wise aëronaut now numbers that project among the roseate illusions of his youth.[1]

Ovid relates a story, doubtless credible in his day, of a clever craftsman who with his son flew bravely aloft, the very first time they put on wings. Daedalus, a Greek architect, having fled from Athens for murder, went with his son Icarus to the island of Crete, where he built the celebrated labyrinth for Minos, the king. He offended that monarch and was cast into prison. In order to escape he made wings for himself and his son, with which they flew far over the sea. But Icarus, in his elation, soared too near the sun, ruined his wings, fell into the sea and was drowned. For proof of this we have the Icarian Sea, named after the unfortunate boy. Also we have Ovid’s charming poem:

In tedious exile now too long detain’d

Daedalus languish’d for his native land;

The sea foreclosed his flight, yet thus he said;

“Though earth and water in subjection laid,

O cruel Minos, thy dominion be,

We’ll go through air; for sure the air is free.”

Then to new arts his cunning thought applies,

And to improve the work of nature tries.

A row of quills, in gradual order placed,

Rise by degrees in length from first to last;

As on a cliff the ascending thicket grows;

Or different reeds the rural pipe compose:

Along the middle runs a twine of flax,

The bottom stems are join’d by plaint wax;

Thus, well compact, a hollow bending brings

The fine composure into real wings.

His boy, young Icarus, that near him stood,

Unthinking of his fate, with smiles pursued

The floating feathers, which the moving air

Bore loosely from the ground, and wafted here and there:

Or with the wax impertinently play’d,

And with his childish tricks the great design delay’d.

The final masterstroke at last imposed,

And now, the great machine completely closed;

Fitting his pinions on, a flight he tries,

And hung self-balanced in the beaten skies.

Then thus instructs his child: “My boy, take care

To wing your course along the middle air:

If low, the surges wet your flagging plumes;

If high, the sun the melting wax consumes.

Steer between both: nor to the northern skies,

Nor South Orion, turn your giddy eyes,

But follow me; let me before you lay

Rules for the flight, and mark the pathless way.”

Thus teaching, with a fond concern, his son,

He took the untried wings, and fix’d them on:

But fix’d with trembling hands; and, as he speaks,

The tears roll gently down his aged cheeks;

Then kiss’d, and in his arms embraced him fast,

But knew not this embrace must be the last;

And mounting upward, as he wings his flight,

Back on his charge he turns his aching sight;

As parent birds, when first their callow care

Leave the high nest to tempt the liquid air;

Then cheers him on, and oft, with fatal art,

Reminds the stripling to perform his part.

These, as the angler at the silent brook,

Or mountain shepherd leaning on his crook,

Or gaping ploughman, from the vale descries,

They stare, and view them with religious eyes,

And straight conclude them gods; since none but they

Through their own azure skies could find a way.

Now Delos, Paros, on the left are seen,

And Samos, favour’d by Jove’s haughty queen;

Upon the right, the isle Lebynthos named,

And fair Calymne for its honey famed.

When now the boy, whose childish thoughts aspire

To loftier aims, and make him ramble higher,

Grown wild and wanton, more embolden’d flies

Far from his guide, and scars among the skies:

The softening wax, that felt a nearer sun,

Dissolved apace, and soon began to run:

The youth in vain his melting pinion shakes,

His feathers gone, no longer air he takes:

“Oh! father, father!” as he strove to cry,

Down to the sea he tumbled from on high,

And found his fate; yet still subsists by Fame,

Among those waters that retain his name.

The Father, now no more a father, cries:

“Ho, Icarus! where are you?” as he flies;

“Where shall I seek my boy?” he cries again,

And saw his feathers scatter’d on the main;

Then cursed his art; and funeral rites conferr’d

Naming the country from the youth interr’d.

How tender and apprehensive that gentleman’s farewell, compared with the modern vogue in like circumstances! Of the two Americans at Berlin who fell four thousand feet in a balloon, it is not recorded that they either kissed or wept.[2] But some Teutonic Ovid may yet adorn the tale with quaint embellishments.

Taking more serious note of Daedalus, it will be observed that he has had few imitators. It is because he never really flew, and no one else can fly, in such manner. That is to say, no man can achieve practical flight on wings actuated by his own muscular power. It may be physically possible for an athlete putting forth herculean energy for a few seconds to sustain himself on wings of enormous spread; but in every lightest zephyr he would be as helpless as a thistle seed.

The actual area of wing required for a man of given weight and power may be roughly estimated; at least its lower limit of size can be determined. Lord Rayleigh,[3] on purely theoretical ground, has computed that a man operating a screw propeller 280 feet in diameter, moving without frictional loss, could sustain his weight for a period of eight hours a day at a comfortable rate of work. But that estimate does not include the weight of the propeller. By exerting ten times his normal power the man could support his weight with a 28-foot propeller.

The physical basis of the computation is the same for every type of flyer, whether bird, man, or machine. Its weight must be sustained by hurling the air downward. The humming bird in its aërial pause, the bee floating beside a blossom, rests on a down-driven column of air. The home-gliding eagle at dusk may encounter a medium in stillest repose, but he leaves behind him a down-flowing wake, viewless, maybe, but none the less real. In all cases the downward impulse per second given to the air must equal the weight supported by its reaction. If the wings be very extensive a proportionate mass of air may be struck down, and yield support with so much the less exertion.

Horizontal flight promises little more than direct screw lift, with the feeble energy of the human muscle. The best modern aëroplanes carry less than 100 pounds per horse power, while an average man must weigh, with a light machine, not less than 200 pounds, and must therefore exert upwards of two horse power during flight. Such an output of energy would exhaust a powerful athlete in a few seconds. Hence from every point of view it appears that Daedalean flight, which still has its devotees in some form, was and always will be utterly impracticable.

Ruskin finds another objection to the disciples of the winged arm. In his disquisition on the equilibrium of angels he complains that those of the traditional two-wing type are devoid of gravitational balance. Such creatures vex the imagination with apprehensions for their stability; hence they cannot be entirely beautiful. The centroid of an angel is in the small of its back, whereas the center of wing support is well forward; therefore the horizontal poise is absurd and unæsthetic. The scientific artist, consequently, views with pain the picture of a fair lady floating level through space supported only at her front end.

Milton adroitly forestalls this censure. In the conception of his glorious Raphael, he provides consummately for uniform and adequate support:

Six wings he wore, to shade

His lineaments divine; the pair that clad

Each shoulder broad, came mantling o’er his breast

With regal ornament; the middle pair

Girt like a starry zone his waist, and round

Skirted his loins and thighs with downy gold,

And colors dipped in Heaven; the third his feet

Shadowed from either heel with feathered mail,

Sky-tinctured grain. Like Maia’s son he stood,

And shook his plumes, that heavenly fragrance filled

The circuit wide.

Leonardo da Vinci, who was a gifted engineer as well as an artist, devised a flying gear for man which shows some dynamic improvement over the mechanism of the old-time angels, flying gods, and hobgoblins. As shown in the accompanying sketch, it provided for gravitational balance by use of an expanding tail projecting well to the rear. Moreover, the propulsion was to employ both arms and legs. This design is considered very remarkable for the time in which it was produced, probably a few years before the discovery of America; and yet it is but one of Da Vinci’s quaint aëronautical inventions, as will appear later.

A less futile scheme of aviation may be to saddle the birds. If one eagle can float a child, a few may possibly carry a man. They are physically able; they are inexpensive; they are unwearied, nimble, swift. Some harness, some tuition may be required; but these come to the industrious. Apparently, such locomotion is a sport worth developing; a royal art, if you please; for who would not course the sky in a purple palanquin borne by imperial eagles?

Kai Kaoos, the King of Persia, is credited with a voyage of this kind, as described in the Shah-Nemeh, or King-Book, written in the tenth century:

“To the king it became a matter of great concern how he might be enabled to ascend the heavens, without wings; and for that purpose he consulted the astrologers, who presently suggested a way in which his desires might be successfully accomplished.

Fig. 1.—Da Vinci’s Designs for Human Flying-Gear.

“They contrived to rob an eagle’s nest of its young, which they reared with great care, supplying them with invigorating food.

“A frame of aloes-wood was then prepared, and at each of the four corners was fixed perpendicularly a javelin surmounted on the point with the flesh of a goat. At each corner again one of the eagles was bound, and in the middle the king was seated with a goblet of wine before him. As soon as the eagles became hungry they endeavored to get at the goat’s flesh upon the javelins, and by flapping their wings, and flying upwards they quickly raised the throne from the ground. Hunger still pressing on them, and still being distant from their prey, they ascended higher and higher in the clouds, conveying the astonished king far beyond his own country. But after a long and fruitless exertion, their strength failed them, and, unable to keep their way, the whole fabric came tumbling down from the sky, and fell upon a dreary solitude in the Kingdom of Chin, where Kai Kaoos was left a prey to hunger, alone, and in utter despair.”

One might prefer a single bird, which could be ridden bareback by a man or woman of common equestrian skill. The early philosophers, therefore, sought with some care for such a creature. The following is related by Bishop Wilkins:

“Cardan and Scaliger doe unanimously affirm, that there is a bird amongst the Indians of so great a bignesse, that his beak is often used to make a sheath or scabbard for a sword. And Acosta tells us of a fowl in Peru called Condores, which will of themselves kill and eat up a whole calf at a time. Nor is there any reason why any other body may not be supported and carried in the air, though it should as much exceed the quantity of these fowls as they do the quantity of a flie. Marcus Polus mentions a fowl in Madagascar which he cals a Ruck, the feathers of whose wings are 12 paces, or threescore foot long, which can with as much ease scoop up an elephant as our kites do a mouse. If this relation was anything credible, it might serve as an abundant proof for the present quaere.”

As the roc has proved a myth, one questions whether a saddle bird may not be evolved by judicious breeding. But opposed to this is the square-cube law of the Greek geometer, by which a learned geologist demonstrated that nature has reached the limit of her resources in the production of large flyers, the ostrich, for example, being too bulky to navigate at all. As a last resource, then, the human dwarf may breed his weight downward to accommodate the bird. Assuredly, the most powerful flyer can carry the lightest human dwarf without difficulty.

Such aërial cavalry has been projected occasionally, and if fairly developed might have interesting employment. Its military value, to say nothing of its civil uses, would be considerable. An aërial scout that could hide in a tree top, or small cloud, then flit home with full intelligence of the enemy, would be effective and unique. In aggressive warfare it would serve the plan of that ingenious Englishman who proposes to repel a German invasion by dispatching birds to peck holes in the enemy’s war balloons. But here the dwarf might be omitted, if the birds were taught to have a definite interest in attacking aërial cruisers with their beaks, or with steel-armed spurs like those of the Spanish fighting cock, or with talons treated chemically to strike fire. Sparrows with sulphur-pointed toes could easily annihilate an aërial squadron at all combustible.

Recurring to the geologist, it may be added that, having discovered the major limit of feathered navigators, he concluded, as a corollary, that human flight is forever impossible. That was in the latter eighties. In 1901 a versatile astronomer adduced the same law to prove that an aëroplane could not be made to carry a man. Presently, learning that this had been achieved, he proved, in a second mellifluous paper, that an aëroplane could not carry, several men.[4] Having erred twice, he wrote a final article announcing that a flyer is fatuous, anyhow, because she cannot repair her engines in the sky!

Fig. 2.—A Possible Air-scout.

Of the numerous daring and industrious inventors who, during remote generations, have launched themselves in the air on some species of rigid or vibrant wings, a few were men of considerable equipment in philosophy, or mechanics, and enjoyed a sufficient measure of success to deserve passing notice; though it seems that no man before the middle of the eighteenth century made a permanent contribution to the real art of mechanical flight, if we except the ingenious suggestive devices of Leonardo da Vinci. However skilfully their flying apparatus may have been planned, or operated, the results were lost to the world, due to inaccurate or inadequate description. Such inventors were J. B. Dante, in the fifteenth century, and the Marquis de Bacqueville, in the seventeenth. Each of these made one, or more, considerable flights, if we may credit the unwavering testimony of their contemporaries; but neither has left a sketch of his device, nor a school of followers to continue his spectacular practice.

Jean-Baptiste Dante, a shrewd observer and profound mathematician, who flourished toward the end of the fifteenth century, a contemporary of Da Vinci and Columbus, is reported by the historians of that day to have sailed successfully through the air on nonvibrant wings designed by himself after a careful study of the great soaring birds. Perching above a steep crag on the shore of Lake Trasimene, he set his wings to the wind at a nice angle, as one sets the sails of a vessel; then, lifted by the swelling breeze, he rose grandly aloft and floated far over the waters. Again and again he repeated the experiment, until the fame thereof secured for him a request to make the demonstration at the marriage fêtes of the illustrious general, Barthelmi Alviano. He accepted the invitation, and, starting from the top of the highest tower in the city of Perugia, he sailed over the public square, and balanced himself for a long time in space, amid the shouts and acclamations of the multitude, attracted to Perugia by the novelty of his performance. But, sad to relate, the very first time he performed these wonderful maneuvers above the solid ground instead of the lake, one of the levers used to alter the impact angle of his wings gave way, disturbing his aërial poise, and causing him to pitch down upon Notre Dame church, breaking one of his legs. After this he taught mathematics at Venice, where he died of fever at the age of forty years.

In 1742, the Marquis de Bacqueville, at the age of sixty-two years, announced that on a certain day he would fly from his house on the Seine, traverse the river, and land in the Garden of the Tuileries. A great multitude assembled, crowding both shores and the two bridges. At the appointed moment the Marquis appeared with his pinions, and launched himself from the terrace. He sailed forth in majestic and serene poise, on graceful wings not unlike those of the traditional angels. He was gliding directly toward the Tuileries, and he enjoyed a happy cruise quite to the middle of the river. Then something happened; his movements became fitful and uncertain; he plunged downward and broke his leg on a laundry boat. The reason for his stopping there can only be surmised, for he had nothing to report. He did not quite fulfil his program, but he flew nine hundred feet delightfully, and he landed without getting wet.

Commentators have marveled as to the nature of the mechanism used by Dante and by De Bacqueville. Historians have strongly attested the fact of the flights, but have overlooked the means. The inventors must have employed aërial gliders of some kind, for adequate motive power was not available before the end of the nineteenth century. Even as an experiment in gliding, or soaring, the achievement of Dante was most daring and wonderful, eclipsing the best performances up to the twentieth century. It is strange that in that period of science the survivor of such an experience, and a college professor, should not have left to the world a careful account of such an extraordinary performance. The alleged flights, however, were unquestionably feasible, even in that remote period, for the construction of an aërial glider is a simple task not beyond the capacity of craftsmen in the fifteenth century A.D., or even the fifteenth century B.C., directed by a skilful designer.

Besides the wing-armed scheme of flight credited to Daedalus, and contemplated by Da Vinci, various other plans were evolved in succeeding years. Aërial chariots and flying machines were devised for the more advantageous use of muscular energy. In all these, of course, the passenger could be both power plant and captain of the ship.

One of the earliest authenticated devices of this kind was the invention of Blanchard, described by him in the Journal de Paris, August 28, 1781, nearly two years before the invention of the hot-air balloon, of which he became later an enthusiastic votary. As his device is but one of a large number that appeared before the close of the nineteenth century, and the advent of light motors, the reader who wishes fuller acquaintance with man-driven airships may be referred to Mr. Chanute’s book, entitled Progress in Flying-Machines, which describes a large variety of such inventions, and discusses the merit and weakness of each.

Blanchard prefaces the description of his machine by answering some criticisms of his project, apparently ventured by his neighbors. “They object to me,” he writes, “that flying is not the business of man, but rather of the feathered birds. I reply that feathers are not at all necessary to the bird for flight; any fabric suffices. The fly, the butterfly, the bat, etc., fly without feathers and with fanlike wings of material resembling horn. It is, then, neither the material nor the form that causes flight, but the volume and the celerity of the movement, which should be as lively as possible.

“They object, moreover, that a man is too heavy to lift himself alone with wings, much less in a vessel which of itself presents enormous weight. I reply that my ship is extremely light; as to the man’s weight, I pray that attention be given to that which M. de Buffon says in his Histoire Naturelle, on the subject of the condor; this bird, though of enormous weight, easily lifts a two-year-old heifer weighing at least a hundred pounds, the whole with wings of about thirty to thirty-six feet expanse.”

He then describes the vessel as a little ship four feet long by two feet wide, having on either side two posts, each supporting a wing ten feet long, the whole forming a parasol twenty feet in diameter. The construction was illustrated by an engraver, who had seen the vessel and was convinced of its practicability. In conclusion, the inventor writes that people shall see him cleave the air with more speed than the crow, and that without losing his breath, being protected by a pointed mask of peculiar construction. But, as he failed to make good his promises, he was subjected to ridicule, as well as praise, by the local press, one of the caricatures portraying him in the act of making an ascension before a concourse of bulging-eyed savants and long-eared jackasses, wearing spectacles to accentuate the appearance of wisdom and solemnity.

The scientific coterie of Paris were apparently impatient of the attention shown Blanchard by the press and people. Accordingly, in May, 1782, the distinguished astronomer, De Laland, of the French Academy, administered a mild rebuke to the editors of the Paris Journal. “Gentlemen,” he wrote, “you have given so much time to air ships and divination rods that one might eventually think that you believe in these follies, or that the scientists who coöperate with your journal have nothing to say to dispel these absurd pretensions. Permit me, therefore, gentlemen, to occupy some lines in your journal to assure your readers that if the savants are silent it is only because of their contempt.

Fig. 3.—Blanchard’s Flying-machine.

“It has been demonstrated to be impossible for a man in any manner whatever to raise himself, or even to sustain himself, in the air. M. Coulomb, of the Academy of Sciences, at one of our meetings a year ago, read a paper in which he showed clearly, by calculating the power of a man, determined by experiments, that he would require wings two or three thousand feet long moved three feet per second; hence no one but an ignoramus would make an attempt of this kind.”

Not many months after this lofty deliverance, Blanchard took De Lalande up in a balloon—“the dead borne by the dumb.”

Coulomb’s calculation that a man’s pinions should be half a mile long must have been discouraging to those inventors who believed in him; for, granting that such wings could lift a man, who could lift the wings? And at that date the steam engine was only beginning to develop; the petroleum engine was hardly thought of. No wonder that people turned eagerly to the balloon when it finally appeared.

There has been some controversy as to what person first clearly conceived a feasible design for a balloon. The conception was certainly not new to the world in 1783, when Joseph Montgolfier made his classical experiment. Indeed, prior to that date three distinct principles of aërial flotation had been entertained by natural philosophers; first, that a boat could be so formed of heavy material as to ride on the upper surface of the atmosphere, as a metallic vessel floats on the water; second, that a closed hull, comprising a partial, or complete, vacuum, could be made light enough to rise; third, that a bag could be made buoyant by filling it with material lighter than air. Of course, it is now clear to men versed in mathematics that only the light-gas principle is mechanically applicable. But the vacuum principle still has adherents among inventors who are too “practical” to understand, or trust, exact computation; and the first principle, though now discarded by everyone, was plausible enough, even to accomplished scientific men, before the experiments of Torricelli, and his invention of the barometer, made in 1643. It may, therefore, be interesting to notice some of the proposed, or reported, air ships based upon these various principles. The following is from Mendoza, Viridario, libri III, probl. 47:

“Any brass vessel full of air, which otherwise would sink, is sustained on the surface of the water, though naturally of much greater specific gravity; consequently a wooden ship, or one of any other material, placed on the summit of an aërial superficies and filled with elementary fire, will be sustained in that position till the gravity of the vessel becomes greater than the sustaining power of the fire it contains.”

This is a clear scientific exposition of a plan for navigating the atmosphere on its upper surface, assuming a distinct upper surface to exist. In commenting on this passage, the Jesuit Schottus, in his Magia Universalis, uses an expression which indicates his belief that a vessel can be made to float in the air by filling it with ether, or the element of fire. He says:

“In such terms has this matter been treated by Mendoza (died 1626); nor is there any improbability involved in his view, whether the element of fire be placed above the air, or, what is still more credible, the ether—that is, the purest air. Although any wood, iron, copper, lead, and such like metals are weightier than an equal volume of water, and for that reason will sink in water when placed there alone, yet if fabricated into hollow shapes, and filled with our impure and heavy air, they swim upon waters, and are adapted to the construction of ships, and are sustained by water without danger of immersion; thus, although these bodies are of greater specific gravity than our air, nevertheless, when shaped into a boat and filled with that very light material, they can float in the air, and are suitable material for the construction of small ships, because the entire work composed of the little ship and the ether can be made lighter than an equal volume of our impure air, even in the highest region.”

As Roger Bacon proposed a similar device in 1542, Mendoza’s was not entirely new and may not have been original. Bacon, describing his aërial vessel, says: “It must be a large, hollow globe of copper, or other suitable metal, wrought extremely thin, in order to have it as light as possible. It must then be filled with ‘ethereal air or liquid fire,’ and then be launched from some elevated point into the atmosphere, where it will float like a vessel on water.”

In the year 1646 another learned Jesuit published a book, Ars Magna Lucis et Umbræ in Mundo, in which he relates an episode indicating that one of his order had made use of a hot-air balloon to intimidate some ignorant pagans. The following demonstration, if reported by a modern missionary, would be accepted as a matter of course; why, then, should we gravely question the story, since it describes an achievement quite possible at the time, assuming that the necessary materials were available? And even assuming the report to be fictitious, still it is a scientific description of a practicable hot-air balloon, presented and credited by a learned scholar and accomplished mathematician more than a century before the balloon was publicly exhibited by the illustrious Frenchmen. He writes:

“I know that many of our fathers have been rescued from the most imminent dangers amongst the barbarians of India by such inventions. These were cast into prison, and whilst they continued ignorant of any means of effecting their liberation, some one, more cunning than the rest, invented an extraordinary machine, and then threatened the barbarians, unless they liberated his companions, that they would behold in a short time some extraordinary portents, and experience the visible anger of the Gods. The barbarians laughed at the threat. He then had constructed a dragon of the most volatile paper, and in this he enclosed a mixture of sulphur, pitch, wax, and so artistically prepared all his materials, that, when ignited, it would illumine the machine, and exhibit the following legend in their vernacular idiom, The Anger of God. The body being formed and the ingredients prepared, he then affixed a long tail, and committed the machine to the heavens, and, favored by the wind, it soared aloft towards the clouds. The spectacle of the dragon so brilliantly lit was terrific. The barbarians, beholding the unusual motion of the apparition, were smitten with the greatest astonishment, and now, remembering the threatened anger of Deity and the words of the father, they were in fear of expiating the punishment he had prognosticated for them. Therefore, without delay, they threw open the gates, they suffered their prisoners to go forth in peace and enjoy their freedom. In the meantime the fire seized on the machine and set it in a blaze, and with an explosion, which was interpreted as an expiring declaration of satisfaction, it, apparently of its own accord, vanished from sight, as if it had accomplished its supernatural mission. Thus the fathers, through the apprehension which this natural manifestation inspired, obtained that which could not be purchased with a large amount of gold.”

Perhaps the reader will permit another anecdote, not entirely for its scientific value, but because he may like to compare the attitude of people toward aërial navigation in the dark ages with the attitude of his neighbors at the opening of the twentieth century. In two histories by Jef le Ministre and De Colonia, of the town of Lyons, the following account is given:

“Toward the end of Charlemagne’s reign, persons who lived near Mount Pilate in Switzerland, knowing by what means pretended sorcerers traveled through the air, resolved to try the experiment, and compelled some poor people to ascend in an aërostal. This descended in the town of Lyons, where they were immediately hurried to prison, and the mob desired their death as sorcerers. The judges condemned them to be burned; but the Bishop Agobard suspended the execution, and sent for them to his palace, that he might question them. They answered: ‘Qu’ils sont du pays meme, que des personnes de consideration les ont forcés de se laisser conduire, leur promettent qu’ils verroient des chose merveilleuses; et qu’ils sont veritablement descendu par l’air.’ Agobard, though he could not believe this fact, gave credence to their innocence, and allowed them to escape. On this occasion he wrote a work on the superstition of the time, in which he demonstrated the impossibility of rising in the air; that it is an error to believe in the power of magic; and that it has its existence in the credulity solely of the people.”

One of the first men to make an aërial model like a fire balloon was the celebrated Brazilian, Bartholomeo-Lourenco de Gusmao, who in his day was nicknamed the “flying man,” and who is reported to have made a remarkable experiment in aërial locomotion at Lisbon. The following account of it is found in a manuscript of Ferreira:

“Gusmao made his experiment on August 8, 1709, in the court of the Palace of the Indies, before his majesty and a large and distinguished audience, with a globe which lifted itself softly to the height of the hall of the Ambassadors, then descended in like manner. It was borne up by certain materials which burned and which the inventor himself had ignited.”

All the details of this description, which was written a generation or more before the Montgolfier experiment, suggest at once a hot-air balloon. But a note printed in 1774 and cited by Cavallo explains that the globes must have been transported by gas. It is certain that early in 1709 Gusmao applied to the King for a patent and sole right to some such invention, desiring an injunction and severe penalty against all infringements. The application sets forth a machine capable of journeying through the air faster than over land or sea, competent to carry messages five or six hundred miles a day to troops, or the most distant countries, and even adequate to explore regions about the poles. Quite a modern promoter Señor Gusmao. The King in reply issued the following decree:

“Agreeably to the advice of my council, I order the pain of death against the transgressor. And in order to encourage the suppliant to apply himself with zeal toward improving the machine which is capable of producing the effects mentioned by him, I also grant him the first Professorship of Mathematics in my University of Coimbra, and the first vacancy in my College of Barcelona, with the annual pension of 600,000 reis during his life.”

The “patent” seemed liberal enough, and yet Gusmao never resumed his aërial experiments. He was accused of magic, and may have feared persecution on that account; accordingly he engaged in naval construction till 1724, when he left Portugal.

The first vacuum balloon was proposed by the Jesuit father, Francis Lana, and described in his book Podromo dell’Arte Maestra Brecia, which appeared in 1670. Though not a practical project like Gusmao’s, it was very ingenious, and marks an interesting phase in the evolution of the fundamental idea of the air ship, or “balloon” as it was called by the inventor, who then coined the word now in common use. Lana proposed to use four copper spheres each 25 feet in diameter and 1/225 inches in wall thickness, quite well exhausted of air, to give ascensional force which he computed at 1,200 pounds aggregate for the four spheres. From these he would suspend the passengers in a boat having a mast and sail to propel the ship in time of favorable wind. Having computed the buoyancy according to well-known physical laws, he could see no possible objection to his project “unless,” he writes, “it be that God would never permit this invention to be practically applied, in order to prevent the consequences that would ensue therefrom in the civil and political government of men.”

Fig. 4.—Lana’s Proposed Vacuum Balloon.

Of recent years inventors having less delicate scruples about embarrassing Providence, have revived Lana’s project with improvements. It has been proposed to replace the sail by a motor-driven propeller, and to ensure the hull against collapse from the prodigious external air pressure—a ton per square foot—by ample internal bracing. Even within the past twelve months this scheme has been soberly advocated by several technical journals and by the author of an elaborate book on aërial warfare. To a mathematician this is amusing, when not too pathetic; for it can be rigorously proved that no vacuum balloon of present day material, whatever its design, can possibly resist crushing if made light enough to float.

In 1887 Walter Wellman described in the Associated Press a steel vacuum balloon 144 feet in diameter and 654 feet long in which a Chicago doctor proposed to carry passengers to the North Pole, at incredible speed, if they would furnish him $130,000 to meet the expenses of construction. “Here is a most excellent opportunity,” wrote Wellman, “for all who would like to win fame by being one of the party which shall set foot upon that icy ignis fatuus of many nations and two centuries.” Two decades later Mr. Wellman organized, after his own ideas, an aërial expedition to the North Pole; but he no longer favored starting from Chicago in a vacuum balloon with a party of stockholders.

It may be added that the inventor of the great steel vacuum balloon, after organizing the Trans-Continental Aërial Navigation Company, and failing to raise all of the $130,000, sought aid from the national government. Here was an interesting situation; a doctor ignorant of mechanics, with the plans for a mammoth and impossible balloon, appealing for aid to a congress, supremely shy of air ships, even though recommended by its ablest military advisers. But in this case there was a capable lobby. The bill for this physically impossible balloon actually passed the House, and was finally defeated only by the timely effort of a few scientific men who, by easy calculation, proved the absurdity of the invention. As the reader may like to see a mathematical proof of the impossibility of a vacuum balloon, since such projects arise frequently, the argument is given in [Appendix I].

PART I
GROWTH OF AËROSTATION

CHAPTER I
EARLY HISTORY OF PASSIVE BALLOONS

Oh, that I could as smoke arise,

That rolls its black wreathes through the air;

Mix with the clouds, that o’er the skies

Show their light forms, and disappear:

Or like the dust be tossed

By every sportive wind till all be lost!

—Æschylus.

If desire is sometimes the mother of invention, doubtless the wish to “mix with the clouds,” or “as smoke arise,” suggested to man his first means of aërial locomotion. Indeed this is openly avowed by Joseph Montgolfier. “Smoke rises in the chimney; why not encage this smoke, and have an available force.” But before describing his fundamental experiments of 1783, let us notice the less conspicuous ones, though not less philosophical, of his immediate predecessors in the development of aëronautic science.

It has been seen, that many years before 1783, inventors had clearly conceived the true principle of the balloon, and would be glad to avail themselves of an element of sufficiently low specific gravity for aërial flotation. The desired opportunity came when, in 1766, Henry Cavendish published his experiments, proving that hydrogen is many times lighter than air. Immediately after this, Dr. Black, the famous chemist and natural philosopher of Edinburgh, conceived the idea that a thin light vessel filled with hydrogen should be able to float and rise in the atmosphere, ideas that he conveyed to his friends and expressed in his lectures a year or two after the appearance of Cavendish’s publication. But he contented himself with merely pointing the way to an obviously practicable invention, leaving, as a university professor should, the development of the scientific idea to inventors and constructive engineers.

Intermediate between Dr. Black, the pure scientist, and the Montgolfier brothers manufacturers, came Tiberius Cavallo, an Italian philosopher living in England, who made the first small hydrogen balloons. In a note presented to the Royal Society of London, June 20, 1782, he relates experiments that seem to entitle him to all the credit of inventing the balloon except success on a practical scale. He made hydrogen soap bubbles which rose beautifully in the air, an experiment that has been repeated throughout the world in every chemical laboratory since his day. He made a variety of gum bubbles and varnish bubbles inflated with hydrogen; but curiously enough these failed to rise, though it is known that such bubbles can be made to float handsomely.[5] He inflated carefully prepared gold-beater skin and failed, though gold-beater skin balloons, both large and small, are now a marketable commodity. Finally he constructed paper balloons which he tried to float by use of hydrogen, but without success, though a year later the Montgolfier brothers easily made paper bags arise with hot air, and Professor Charles ascended in a large silk balloon inflated with hydrogen.

The cause of Cavallo’s interesting failures reveals itself in his own account of one of his pioneer experiments. In his History and Practice of Aërostation, he relates that he constructed, of fine Chinese paper, a cylindrical balloon having short conical ends and a calculated buoyancy of twenty-five grains, when properly inflated with hydrogen. This bag, carefully deflated of air by compression between the hands, he suspended above a large bottle connected with it by a glass tube, and supplied with materials for generating hydrogen; in this case a mixture of dilute sulphuric acid and iron filings. When the hydrogen was evolving quite rapidly, he expected to see the paper sac expand and fill out with proportionate speed; but to his surprise it remained perfectly flat, while the room filled with the strong and disagreeable odor of the “inflaminable air.” He then realized that the carefully made sac of paper, which could be so easily inflated with air, was very permeable to hydrogen, allowing it to escape instantly, as through porous cloth, or netting.

Cavallo desisted when the goal was within reach. His plans were practicable, but he abandoned them too readily. Why did he not varnish his balloon when it leaked? He could thus so easily have inaugurated the art of aërial navigation. But after salting the bird’s tail he let it escape.

Various accounts have been given of the steps by which the Montgolfiers were led to their invention of the balloon. They are said to have studied and discussed projects for aërial locomotion a decade before hitting upon their first successful device; at one time filling a paper bag with smoke ineffectually; again with steam, and again trying, but in vain, to employ hydrogen. The following apparently reliable account is given by a friend of the Montgolfiers, Baron Gernando, in his biographical notice of Joseph Montgolfier, having obtained the story from the inventor himself.

Joseph Montgolfier found himself at Abignon, and it was at the time when the combined armies held the siege of Gibraltar. Alone, in the chimney corner, dreaming, as usual, he was contemplating a sort of cut that represented the work of the siege; he grew impatient observing that one could not reach the body of the place either by land or sea. “But could not one arrive there through the air? Smoke rises in the chimney; why not store this smoke in such a manner as to form an available force?” His mind calculated instantly the weight of a given surface of paper, or taffeta; he constructed without delay his little balloon, and saw it rise from the floor, to the great surprise of his hostess, and with a peculiar joy. He wrote on the spot, to his brother then at Annonay: “Prepare immediately a supply of taffeta and cordage, and you shall see the most astonishing thing in the world.”

A quainter story is told by Brisson in his Dictionary of Physics. He says: “I can only repeat what the citizen Montgolfier himself told me, when he came to Paris to announce his discovery; that the citizeness Montgolfier having placed a skirt on an open-wicker basket, such as women use to dry linen, the skirt was lifted to the ceiling. It is from this fact that the citizens Montgolfier started.”

Whatever the preliminaries, the Montgolfier brothers finally made the experiment of holding a paper bag over a fire fed with wet straw and wool. It is doubtful whether they purposed to fill it with smoke, or with hot air or an electrical cloud. They knew that a cloud of some kind rises from such a fire, and they wanted to harness it. Their first balloon took fire and went up as smoke. But they were rich paper manufacturers, and soon had another balloon of 700 cubic feet capacity. This rose from the fire to a height of 1,000 feet, carrying no fuel with it. Thus two practical[6] men had made fire lift a paper sac; let the Academy explain how. The baby Aërostation was born.

How fortuitous the primal steps of science! Galvanism from the twitch of a frog’s leg; aërostation from the puff of a petticoat! There had been no year in thirty centuries when people could not easily have built a hot-air balloon. All the materials were available; only a little thought was wanting. A simple sketch sent to a Roman tailor, or tent-maker, could have furnished a woven bag competent to lift passengers from the heart of the Coliseum, to the wonder and delight of a hundred thousand spectators. Yet the genius that could design the Coliseum, or cover its vast enclosure with canvas, failed to think of the magic bag that would have enhanced so much the ingenious shows of a show-loving people. That device was an inspiration destined to a common Frenchman at no uncommon period of science. The hydrogen balloon arrived in the natural and logical order of scientific progression; but the hot-air bag might have presented itself at any time since the birth of weaving. It was a happy thought, like the ophthalmoscope, or jack-knife—quaint modern creations of constant use or comfort to mankind.

The public inauguration of aëronautics occurred on June 5, 1783, at Annonay, the home of the Montgolfier family, 36 miles from Lyons. The states of Vivarais being assembled at that place, were invited to witness the ascension. The Deputies and many spectators found in the public square an enormous bag which, with its frame, weighed 300 pounds, and would inflate to a ball 35 feet in diameter. When told that this huge mass would rise to the clouds they were astonished and incredulous. The Montgolfiers, however, lit a fire beneath and let the bag speak for itself. It gradually distended, assuming a beautiful form, and struggling to free itself from the men who were holding it. At a given signal it was released; it ascended rapidly, and in ten minutes attained a height of 6,000 feet. It drifted a mile and a half and sank gently to the ground.

Fig. 5.—Montgolfier’s Experimental Balloon.

When the French Academy learned of this event they desired to have an ascension in Paris, and at once started a public subscription to defray the expense of constructing and inflating a balloon. They placed the work in charge of the physicist Charles, after inviting the Montgolfiers to Paris, and finding they could not come immediately. Charles proved more than a substitute; he became a fertile inventor and a rival in the new field. Aided by the skill of the Robert brothers, he made a silk globe varnished with dissolved rubber, and filled it with hydrogen, which is many times lighter than hot air. The operation of filling occupied three days, consuming 500 pounds of sulphuric acid and half a ton of iron. The globe was 13 feet in diameter, and designated a “balloon,” or big ball. This had next to be moved from the place of filling, in the Place des Victoires, to the Champ de Mars, two miles distant, in order to have space enough to accommodate the increasing crowd of spectators. Accordingly, on the 26th it was conveyed thither, in the dead of night, preceded by lighted torches, surrounded by a cortege, and escorted by foot and horse guards. Impressive and weird, indeed, was this nocturnal caravan of troops and towering globe advancing slowly through the dark and silent streets. The astonished cab drivers knelt humbly, hat in hand, while the procession passed.

The ascent of this, the first hydrogen balloon, was a popular and a memorable event. The field was lined with troops. The curious spectators had thronged every thoroughfare and darkened every housetop. It was an all day festival, inaugurating a peculiarly French science, with French animation. The booming of cannon announced to all Paris the impending flight of the balloon. At five o’clock, in the presence of 50,000 spectators, and in a shower of rain, the balloon rose more than half a mile and entered the clouds. The people overwhelmed with surprise and enthusiasm, stood gazing upward, despite the rain, observing every maneuver till the vessel had ascended and faded from view.

Fig. 6.—Charles’ First Hydrogen Balloon.

The landing of this little balloon did not leave it in a condition to exhibit proudly to future generations. After drifting three quarters of an hour, it fell in a field near Gonesse, a village fifteen miles from the place of ascension, apparently ruptured from overdistention. The villagers flocked about it with curiosity and trepidation, ignorant of its nature, whether of bird kind or monster; and doubtful of its origin, whether natural or satanic. They fell upon it with flails and pitchforks. When struck it smelt strongly of sulphur, indicating a diabolic source. They finally hitched it to the tail of a horse which galloping away in terror, badly damaged it. Whether this destruction was wrought through fear or rustic hilarity, it induced the government of France to issue a notice to the public explaining the innocuous nature of a simple balloon.

In the meantime Joseph Montgolfier, having reached Paris, had constructed a waterproof linen balloon 46 feet in diameter and ornamented in oil colors, which was to be publicly launched at Versailles. On September 19, 1783, the king and queen, the court and a vast throng of people of every rank and age, assembled to witness the ascension. Montgolfier explained to them every detail, and finally lit the fire, about one o’clock. The great bag gradually expanded, rounding out in eleven minutes to a beautiful globular form, tugging upward with a force of seven hundred pounds. Beneath was suspended a wicker cage containing the first aërial passengers—a sheep, a rooster and a duck. The vessel rose majestically above the applauding multitude to a height of fourteen hundred feet, and drifted some two miles in eight minutes, descending gradually in the wood at Vaucresson. The animals were tipped out on landing; but, when found by two game-keepers, they were none the worse for their strange journey. The sheep was grazing and the cock crowing, says one report, while another relates that the sheep had trampled on the rooster and lamed him.

Stephen Montgolfier now wishing to send up human passengers, made a balloon of 100,000 cubic feet capacity. It was shaped like a full lemon pointing upward, with a cylindrical neck below, 16 feet in diameter. Around this neck was a wicker balcony three feet wide, to carry the aëronauts, bundles of straw for fuel, pails of water and sponges to extinguish incipient conflagrations, here and there in the balloon, during a journey. Through stokeholes in the side of the neck sheaves of straw could be forked to the grate suspended centrally below by radial chains. During inflation the base of the balloon rested on a platform, and its top was supported by a rope stretched between two poles. The vessel when completed, in a garden of the Faubourg St. Antoine, was 85 feet high by 48 feet across, and weighed 1,600 pounds. About its zone, painted in oil, were elegant decorations; portraits, cyphers of the king’s name, fleur-de-lis, with fancy borders below and above; while higher still, on the arching dome of the bag, were all the signs of the celestial zodiac.

The handsome vessel was now ready; but what daring captain should navigate her? King Louis proposed two prisoners who were under sentence of death, and had to be killed somehow. But the brave Pilâtre de Rozier protested indignantly: “Eh quoi! de vils criminels auraient les premiers la gloire de senlever dans les airs! Non, non, cela ne sera point.” He stirred up the city, and finally prevailed, through the entreaties of the Marquis d’Arlandes, who secured from the king permission to accompany his friend.

After some days of preliminary practice in maneuvering the tethered balloon, these gentlemen were ready for an aërial voyage. On November 21, 1783, the balloon was inflated in the garden of La Muette palace, and stocked with enough straw for an hour’s journey. When all was ready Pilâtre de Rozier and the Marquis d’Arlandes stepped with eager courage into the gallery taking opposite sides to ensure proper balance. At two o’clock they rose splendidly, amid the acclamations of a vast throng of spectators, and at the height of 280 feet, removing their hats, saluted the surprised multitude. Encountering a south blowing wind, they drifted five miles in some twenty minutes, and landed safely in a field. The apparatus was soon assembled on a cart and returned to the Faubourg St. Antoine, where it was originally constructed. The details of this first human voyage in a balloon are very interesting and well told in a letter written by the Marquis d’Arlande to a member of the French Academy.

Fig. 7.—Montgolfier’s Passenger Balloon.

“At this time M. Pilâtre said: ‘You do nothing, and we shall not mount.’ ‘Pardon me,’ I replied. I threw a truss of straw upon the fire, stirring it a little at the same time, and then quickly turned my face back again; but I could no longer see La Muette. Astonished, I gave a look to the direction of the river.... M. Pilâtre then said, ‘See, there is the river, and observe that we descend.’ ‘Well, then, my friend, let us increase the fire;’ and we worked away. But instead of crossing the river, as our direction seemed to indicate, which carried us over the house of the Invalides, we passed along the island of Cygnes, reëntered over the principal bed of the river, and advanced up it as far as the gate de la Conference. I said to my intrepid companion: ‘See, there is the river &c.’ I stirred the fire, and took with the fork a truss of straw, which from being too tight, did not take fire very easily. I lifted it and shook it in the middle of the flame. The next moment I felt as if I were lifted up from under the arms, and said to my companion, ‘Now we mount, &c.’ At the same time I heard a noise toward the top of the machine, as if it were going to burst; I looked, but did not see anything. However, as I was looking up, I felt a shock, which was the only one I experienced. The direction of the motion was from the upper part downwards. I said then: ‘What are you doing? Are you dancing?’ ‘I don’t stir,’ said he. ‘So much the better,’ I replied, ‘it is then a new current, which, I hope, will push us over the river.’ In fact, I turned myself in order to see where we were, and I found myself between l’École Militaire and les Invalides, beyond which place we had already gone about 2,500 feet. M. Pilâtre said at the same time: ‘We are on the plain.’ ‘Yes,’ said I, ‘and we advance.’ ‘Work on,’ said he. I then heard another noise in the machine, which appeared to be the effect of a rope breaking. This fresh admonition made me examine attentively the interior of our habitation. I saw that the part of the machine which was turned toward the south was full of round holes, many of which were of a considerable size. I then said: ‘We must descend,’ and at the same time I took the sponge and easily extinguished the fire, which was round some holes that I could reach; but leaning on the lower part of the linen, to observe whether it adhered firmly to the surrounding circle, I found that the linen was easily separated from it, on which I repeated that it was necessary to descend. My companion said: ‘We are over Paris.’ ‘Never mind that,’ said I, ‘but look if there appears any danger for you on your side—are you safe?’ He said: ‘Yes.’ I examined my side, and found that there was no danger to apprehend. Farther, I wetted with a sponge those cords which were within my reach. They all resisted, except two, which gave way. I then said: ‘We may pass over Paris.’ In doing this, we approached the tops of houses very sensibly; we increased the fire, and rose with the greatest ease. I looked below me, and perfectly discovered the Mission Étranger. It seemed as if we were going toward Saint-Sulpice, which I could perceive through the aperture of our machine. On rising a current of air made us leave this direction, and carried us toward the south. I saw on my left a sort of forest, which I took to be the Luxembourg; we passed over the Boulevard, and then I said: ‘Let us now descend.’ The fire was nearly extinguished; but the intrepid M. Pilâtre, who never loses his presence of mind, and who went forward, imagining that we were going against the mills that are between Petite Gentilly and the Boulevard, admonished me. I threw a bundle of straw on the fire, and shaking it in order to inflame it more easily, we rose, and a new current carried us a little toward our left. M. Rozier said again: ‘Take care of the mills’; but as I was looking through the aperture of the machine, I could observe more accurately that we could not meet with them, and said: ‘We are there.’ The moment after, I observed that we went over a piece of water, which I took for the river, but after landing, I recollected that it was the piece of water, &c. The moment we touched the ground, I raised myself up to the gallery and perceived the upper part of the machine to press very gently on my head, I pushed it back, and jumped out of the gallery, and on turning toward the machine, expected to find it distended, but was surprised to find it perfectly emptied and quite flattened, &c.”

While the foregoing experiment was in progress, plans were matured for the construction of a hydrogen balloon large enough to support two passengers and remain aloft many hours, without the need of carrying dangerous fuel. This type of balloon, called a Charlière, after its inventor, was destined largely to supersede the hot-air type, known as the Montgolfière, and indeed, to replace it entirely for free voyages of considerable endurance and for most power voyages. The construction after the plan of Professor Charles was delegated to two very intelligent mechanics, the Robert brothers who also had succeeded in dissolving caoutchouc, and thus producing a very superior balloon varnish. The project was first announced in the Journal de Paris of the 19th of November 1783. As usual in those days of public enthusiasm, a subscription was opened to defray the expenses of the experiment, estimated to cost about ten thousand francs.

Fig. 8.—Charles’ Passenger Balloon.

This balloon was a truly scientific creation, which advanced aërostation from tottering infancy almost to full prime. The bag was a sphere 27½ feet in diameter made of gores of varnished silk. A net covered the upper half and was fastened to a horizontal hoop girding the middle of the globe, and called the “equator.” From the equator depended ropes which supported, just below the spherical bag, a wicker boat measuring eight feet by four, covered with painted linen and beautifully ornamented. The balloon had at the bottom a silk neck 7 inches in diameter, to admit the gas during inflation, and at the top, a valve which could be opened by means of a cord in the boat to let out gas during a voyage, so as to lower the balloon, or to relieve excessive pressure. In the boat were carried sand ballast to regulate the height of ascension, a barometer to measure the elevation, anchor and rope for landing, a thermometer, notebook, provisions, and all the paraphernalia of a scientific voyage. Barring the fancy boat, this is almost a description of a good modern balloon.

The inflation and ascension occurred in the Garden of the Tuileries, where the limp bag was initially suspended from a rope stretched between two trees. For three days and nights the hydrogen, drawn from twenty barrels containing iron and dilute sulphuric acid, poured upward through the silken neck into the distending globe, which swelled in volume to 1,400 cubic feet. Finally on a beautiful day, the first of December 1783, the Tuileries and all the neighborhood were crowded with spectators. A numerous guard of soldiers, stationed about the apparatus and grounds, preserved order. The fashion and nobility of Paris were there, in ample splendor, attracted by the novelty and importance of the experiment, and the fame of the inventor. Shortly before two o’clock Professor Charles presented to his friend, Montgolfier, a pilot balloon six feet in diameter, saying, “It is your prerogative to blaze the way through the sky.” The pilot balloon was released, showing to everyone the direction of the aërial currents. Charles and Roberts stepped into the boat, seated themselves, and quickly rose into the sky. The multitude gazed in silent wonder. Presently they observed two pennants waving high above them, though the navigators were scarcely visible; whereupon they burst forth into wild enthusiasm and thunderous applause.

Immediately a cavalcade set out in hot pursuit of the venturesome sailors. It was the first chase after an air ship, and a most vigorous one. The balloon drifting northwestward at a speed of fifteen miles an hour, crossed the Seine, passed over several towns and villages, to the great astonishment of the inhabitants, and landed in a field near Nesle. Here it was securely held by friendly peasants, to await the advent of the official witnesses. Presently these arrived, drew up a certificate of descent and signed it. The Duke de Chartres, and the Duke de Fitz-James, who had followed less swiftly, now rode up and signed the formal document, to the great gratification of the aëronauts. The aërial journey had been a most delightful one, lasting about two hours and covering nearly thirty miles.

After receiving the felicitations of his friends, Charles determined to reascend, in order to obtain further scientific observations. Owing to leakage and loss of buoyancy, he must now leave behind his pleasant companion. He had proposed replacing with earth, or stones, a part of Mr. Robert’s weight, but, finding none at hand, he signaled the peasants to let go, whereupon he rose with unusual speed. The remainder of this first and very remarkable scientific voyage is well told by the navigator himself:

“In twenty minutes I was 1,500 fathoms high; out of sight of all terrestrial objects. I had taken the necessary precautions against the explosion of the globe, and prepared to make the observations which I had promised myself. In order to observe the barometer and thermometer, placed at the end of the car, without altering the center of gravity, I knelt down in the middle, stretching forward my body and one leg, holding my watch in my left hand, and my pen and the string of the valve in my right, waiting for the event. The globe, which, at my setting out, was rather flaccid, swelled insensibly. The air escaped in great quantities at the silken tube. I drew the valve from time to time, to give it two vents; and I continued to ascend, still losing air, which issued out hissing, and became visible, like a warm vapor in a cold atmosphere. The reason of this phenomenon is obvious. On earth, the thermometer was 47°, or 15° above freezing point; after ten minutes’ ascent it was only 21°, or 11° below. The inflammable air had not had time to recover the equilibrium of its temperature. Its elastic equilibrium being quicker than that of the heat, there must escape a greater quantity than that which the external dilatation of the air could determine by its least pressure. For myself, though exposed to the open air, I passed in ten minutes from the warmth of spring to the cold of winter; a sharp dry cold, but not too much to be borne. I declare that, in the first moment, I felt nothing disagreeable in the sudden change. When the barometer ceased to fall, I marked exactly 18 inches 10 lines (20-01 in. English), the mercury suffering no sensible oscillation. From this I deduce a height of 1,524 fathoms (3,100 yards), or thereabouts, till I can be more exact in my calculation. In a few minutes more, my fingers were benumbed by the cold, so that I could not hold my pen. I was now stationary as to the rising and falling, and moved only in an horizontal direction. I rose up in the middle of the car to contemplate the scene around me. At my setting out the sun was set on the valleys; he soon rose for me alone, who was the only luminous body in the horizon, and all the rest of nature in shade; he, however, presently disappeared, and I had the pleasure of seeing him set twice in the same day. I beheld, for a few seconds, the circumambient air and the vapors rising from the valleys and rivers. The clouds seemed to rise from the earth and collect one upon the other, still preserving their usual form, only their color was gray and monotonous from the want of light in the atmosphere. The moon alone enlightened them, and showed me that I was tacking about twice; and I observed certain currents that brought me back again. I had several sensible deviations; and observed, with surprise, the effects of the wind, and saw the streamers of my banners point upwards. This phenomenon was not the effect of the ascent or descent, for then I moved horizontally. At that instant I conceived, perhaps a little too hastily, the idea of being able to steer one’s course. In the midst of my transport I felt a violent pain in my right ear and jaw, which I ascribed to the dilatation of the air, in the cellular construction of those organs, as much as to the cold of the external air. I was in a waistcoat and bareheaded. I immediately put on a woolen cap, yet the pain did not go off but as I gradually descended. For seven or eight minutes I had ceased to ascend; the condensation of the internal inflammable air rather made me descend. I now recollected my promise to return in half an hour, and, pulling the string of the valve, I came down. The globe was now so much emptied, that it appeared only a half globe. I perceived a fine ploughed field near the wood of Tour du Lay, and hastened my descent. When I was between twenty or thirty fathoms from the earth I threw out hastily two or three pounds of ballast, and became for a moment stationary, till I descended gently in the field, about a league from the place whence I set out. The frequent deviations and turnings about make me imagine that the voyage was near three leagues, and I was gone about thirty-three minutes. Such is the certainty of the combinations of our aërostatic machine, that I might have kept in the air at least for twenty-four hours longer.”

Further interesting details of the first balloon experiments at Paris are furnished by Dr. Benjamin Franklin, then American Minister to France, in his letters written to Sir Joseph Banks, President of the Royal Society of London, and presented in [Appendix II] of this book. These quaint and substantial stories are well worth perusal as the expressions of a great diplomat and philosopher who, in the midst of social and political activities, found time for scientific correspondence with his friends in both hemispheres.

Aërial navigation was now become a practical art which should advance rapidly in popularity, in both Europe and America. Very soon ascensions were made everywhere, for private amusement and for public exhibitions. Not a few were made for scientific, for military and for topographical purposes; thus giving the art a utilitarian as well as a sporting feature. It will be interesting to note some of the more conspicuous ascensions, voyages and improvements made in passive balloons subsequently to the invention of Montgolfières and Charlières.

The largest hot-air balloon ever constructed, La Flesselle, was launched from the suburbs of the city of Lyons on January 19, 1784, just two months after the ascent of the first human passengers. It was also one of the most troublesome to assemble and keep in repair. Day by day, for more than a week, the balloon was inflated for the purpose of attaching the ropes to support the great gallery. But the wind blew dreadfully at times; rain and snow fell on the machine; frost and ice covered the huge bag; many rents ensued, demanding frequent repairs. On one occasion, when fed too freely with flame from straw sprinkled with alcohol, the monstrous ship rose so vigorously as to drag fifty men with it some distance along the ground. Finally on the 19th of January, when the weather moderated, the operators built small fires under the scaffold below the balloon, and thawed away the ice from the drenched and frozen bag. Then they stocked its gallery with straw and pitchforks, with fire extinguishers, and other provisions for the journey. The inflation beginning about noon, occupied but seventeen minutes. The balloon swelled out rapidly, with the roaring flames ascending inside, and at last stood forth huge and majestic before the admiring multitude—a towering thing of magic growth, 100 feet in diameter by 130 feet high.

The ascension of this gigantic vessel was immensely spectacular; but it was also most adventurous and foolhardy. The great bag, which at best was made of poor materials, was in bad repair after its frequent inflations. But of the six passengers in the gallery not one could be induced to remain behind to lessen the risk to the others. Their pilot, M. de Rozier, remonstrated with them; the proprietor M. C. Flesselle wished them to cast lots; but no one would abandon the journey. So, with fear and reluctance, the pilot ordered the mooring ropes to be cut. Just as the ascent began, a seventh passenger, M. Fontaine, sprang into the gallery and sailed aloft with the others. By vigorous stoking the aërial sailors urged their fiery vessel upward three thousand feet, whence, apparently without fear, they waved their hats to the vast throng below.

Fig. 9.—La Flesselle.

The spectators were now in a frenzy of excitement. For more than a week they had vacillated between hope and disappointment; but now they saw the huge ship soaring into the sky, perhaps on her way to destruction. They heard the blast of martial music and the booming of mortars. Then the accumulated emotion of the multitude burst forth. Exclamations of joy, shrieks of fear, thunders of applause resounded above the sea of people. Finally the balloon began to burst, a dangerous rent running vertically along her side. The machine descended with great rapidity, to the alarm of everyone. It is reported that not fewer than sixty thousand people ran to the place of landing, with the greatest apprehension for the lives of the travelers. But the adventurous men stepped forth from the gallery, after a fifteen minutes’ voyage, without hurt of any kind, save an insignificant scratch borne by Joseph Montgolfier, who on this occasion made his first and last ascension. This was also the first and last ascension of that gigantic fire balloon; for although it furnished a world of delirious emotion and excitement, the trouble of inflating the vessel was too great to be repeated.

The crossing of the English Channel by balloon had been contemplated many months by various adventurous spirits; and at length, on a fine day, the seventh of January, 1785, this feat was attempted by two intrepid men, the French aëronaut, M. Blanchard, and an American physician, Dr. Jeffries, who had graduated at Harvard in 1763, and was practicing medicine in England. Starting from the perpendicular cliff at Dover Castle, at one o’clock, they sailed in the direction of Calais, having with them only thirty pounds of sand ballast. This was too little for so long a voyage; but it would doubtless carry them a few miles, in the favorable breeze then blowing. To their surprise, the atmosphere seemed to grow lighter as they advanced over the water, letting them sink too freely. As they approached mid-channel they were compelled to discharge all their ballast in order to maintain their level. But the balloon still descended, seemingly attracted by the water. Then they ejected a parcel of books to gain a moment’s relief. When three-fourths across the Channel they sighted the French Coast, which now they yearned to see at closer range; for the balloon was contracting and sinking rapidly. They threw out from the boat everything available, wings, anchors, cords, provisions; yet they saw the vessel persistently approaching the sea. Finally they cast off part of their clothing, fastened themselves to the cords suspended from the balloon-ring, and prepared to cut away the boat. But presently approaching the coast near Calais, they began to rise; then ascended rapidly, soaring in a magnificent arch above the high grounds. At last they descended gradually above the forest of Guines, seized the branches of a tree to stop their flight, and at three o’clock were happily landed. It was a thrilling voyage of two hours, and made a profound impression at the time. As a mark of appreciation the King presented Blanchard a sum of 12,000 francs and a pension of 1,200 francs per year. The people erected a monument on the place of landing to commemorate this extraordinary voyage.

This splendid achievement incited two Frenchmen to attempt a counter voyage which ended disastrously. On June 15, 1785, Pilâtre de Rozier and M. Romain set out from Boulogne on a voyage from France to England, in a compound balloon composed of a hydrogen balloon forty feet in diameter, below which was suspended a fire balloon ten feet in diameter. They hoped by judicious stoking of the lower balloon to obviate the sinking tendency suffered by Blanchard and Jeffries. But the smaller globe proved a fatal auxiliary. Scarcely a quarter of an hour after launching, the whole apparatus was aflame at an altitude of 3,000 feet, and presently fell in charred and hideous fragments upon the seashore. M. Romain still showed some signs of life, but Pilâtre de Rozier was completely dead and all his bones were broken. They were the first martyrs in the cause of the new science. Poor De Rozier knew on starting that his apparatus was in bad condition, but he had received for the purpose a sum of money from a distinguished patron, and therefore felt obliged in honor to attempt the voyage. He was twenty-eight years old and engaged to be married to a young lady in the convent at Boulogne, who eight days after the catastrophe which robbed her of her fiancé, died brokenhearted and in convulsions.

CHAPTER II

The next important advance in practical ballooning was made by the substitution of coal gas for hydrogen. This was England’s contribution to an art which previously had not greatly flourished west of the Channel. It was a contribution following the natural growth of science; for in 1814 coal gas began generally to be used for lighting London, and seven years later for inflating balloons. This valuable innovation was made by the famous aëronaut, Charles Green, on the occasion of his first ascension, made July 19, 1821, the coronation day of George IV. The new method largely superseded the old, extending throughout the world with the spread of gas lighting; and it gave a powerful stimulus to aëronautics by rendering inflation cheap and convenient. Mr. Green himself made 526 ascensions during his life, or at the rate of one cruise a month for nearly forty-four years. In due time, every country had its professional aëronauts, and finally its amateurs, who, forming themselves into aëro clubs, devoted themselves to racing in free balloons, inflated quite usually from a city gas supply.

In 1836 Mr. Robert Holland organized an expedition designed to test the utmost capabilities of the balloon of his day, particularly in points of endurance and control. Engaging as pilot the first aëronaut of the age, Mr. Charles Green, and employing the largest gas balloon that ever had been constructed, stocked with provisions enough to last three men a fortnight, he invited a third person, Mr. Monck Mason, to join them on a cruise from London to wherever the wind would take them, but preferably to land near Paris, as the balloon was to be delivered there after the voyage.

Fig. 10.—The Great Balloon of Nassau.

The vessel selected for that famous cruise was The Great Balloon of Nassau, then recently built by Mr. Green and representing all that his skill and experience could devise. It was of pear shape, formed of the finest crimson and white silk, “spun, wove and dyed expressly for the purpose,” and comprising when distended a volume of 85,000 cubic feet. From its stout balloon-ring six feet in diameter was suspended a wicker car measuring nine feet long by four wide, having a seat across either end, and a cushioned bottom to serve as a bed, if such should be needed. Across the middle of the car was a plank supporting a windlass for raising or lowering the guide-rope, that is a heavy rope which could be trailed over land, or water, to keep the balloon at a nearly constant level without expenditure of ballast, and to check its speed on landing. This valuable device invented by Mr. Green in 1820, was now to receive adequate trial, which, indeed, formed one of the chief purposes of the cruise. Other paraphernalia of the voyage were food and drink, warm clothing, lamps, trumpets, telescopes, barometers, a quicklime coffee-heater, a grapnel and cable, and a ton of sand ballast in bags.

The voyage proved well worthy of the elaborate preparations. At one-thirty o’clock on November 7th, the three navigators arose from London, in presence of a mighty multitude, and drifted in a southeasterly direction traversing the cultivated plains of Kent, and in two hours passed the environs of Canterbury. Here they dropped a parachute with a letter for the Mayor, which he duly received. Continuing their journey they floated leisurely above the tree tops, talking to the inhabitants of the country, startling the fleet-winged quail, terrifying a colony of rooks, and finally reaching Dover at sundown, where they again dropped a letter for the Mayor of the city, which also was duly delivered.

Without a moment’s pause they drifted over the Channel into the gathering darkness. Before them rose a huge wall of vapor and black clouds standing on the bosom of the sea; behind them the twinkling lights and the music of breakers rolling on a hospitable shore. Presently they were immersed in a region of absolute silence and impenetrable darkness. At times this deep stratum would slowly dissolve, revealing a glimpse of the dusky ocean and a passing ship; then some huge wreath of vapor would involve them in bottomless gloom, without perspective, without apparent motion, without a sound to cheer or mark their dubious course. Now to avoid the risk of settling too near the sea, as Blanchard and Jeffries had done, they were preparing to let down the guide-rope with floating ballast attached, when suddenly they emerged from the pall of darkness, and were greeted by the glittering lights of Calais, and the gentle sound of waters dashing upon the beach. They had crossed the Channel in one hour, and were soaring serenely three thousand feet above the ocean, not having to lower the guide-rope to preserve their elevation.

Now came the preparations for a night voyage over an obscurely defined land route. A simple rope one thousand feet long without ballast was allowed to trail beneath them. A lamp was lit. Coffee was heated by the slacking of quicklime. An ample store of viands and wine was spread on the board in the middle of the car. The strenuous period of thought and labor was past, and now three hungry men sat leisurely at dinner, after a fast of twelve long hours. However sparing of bones and bottles, which later might serve as ballast, they were not economical of food and wine that evening. For the present they had only to live and be happy as bachelors. Muffled in soft garments, well fed, abundantly served with divine beverages, hot or cold; what finer picture of masculine comfort and delight?

They were now floating tranquilly in the vast solitude of heaven, over a teeming continent mantled in night and mystery. Far along earth’s sable surface gleam the scattered fires of many villages; and above it the lovelier fires of a moonless sky. Unseen, unsuspected, they survey kingdoms and cities, trailing their long rope serpent-like over woodland, field and quiet homestead. Now on the horizon before them looms a greater fire, like a distant conflagration, widening as they approach. Gradually it expands into a model city, shooting out long lines of illuminated streets; here the public squares, markets and theatres; there the rumbling iron mills with blazing furnaces. They are above Liege at her festive hour, murmuring with animation and busy life. Again they drift into the dark regions of slumber, lapped in silence and deep tranquillity, where the lights of men are extinguished, and the stars, redoubling their lustre, gleam whitest silver in heaven’s jetty dome. Midnight involves the world; an abyss of darkness enfolds it; their solitary lamp seems to melt its way through solid space of blackest marble. For hours they undulate over the rolling hills, rising and falling a thousand cubits, held always to earth by the trailing rope. At times they are so near as to trace the landscape dimly; here a white tract covered lightly with snow, here a dark valley or forest, here a tortuous river, probably the Rhine, with its multitudinous thunder of waters. But in all that weird and obscure wandering no joyous note of human or animal life ascends ere dawn to cheer their solitary course in the sky.

At last the paling of the morning star, and a faint tingeing of the eastern cumuli, announce the expected day. With sudden bound the great ship mounts aloft twelve thousand feet, into the glory of the blazing sun, new risen among clouds of amber and purple. Far below, twilight and mist still mantle the half-awakened world, presenting a stupendous panorama, vast as an empire. Presently down they plunge into the vaporous and obscure atmosphere, drifting carelessly, but soon reascending into the splendor of morning. Thus after making the sun rise three times and set twice, they float contentedly along the misty landscape, marveling what region lies below them, whether a barren wilderness, or the abode of civilized life, with human comforts and a ready means of transportation. A hot breakfast would be very welcome now; for they had accidentally dropped the lime pot and had spent the latter half of the night without warm beverage in a region where oil and water had frozen.

At length through the clearing vapor they perceive the country well tilled and populous; a good place to land to shorten their route to Paris, and avoid the wide plains of Poland or Russia. They raise the guide-rope, lower the cable and anchor, open the valve, and descend in a grassy field near Weilburg, in the Duchy of Nassau. It is now seven-thirty o’clock, just eighteen hours since starting; and they have traveled five hundred miles, the longest aërial voyage thus far recorded. Very soon they are surrounded by a wondering crowd of pipe-puffing, shaggy-headed, German peasants, by whose willing aid they finally deflate the balloon, pack it in the bottom of the car, and mount it on a one-horse cart for Weilburg. Thence the aëronauts, after a week of festivities in their honor, and distinguished attentions from the highest officials of the town, embarked with their balloon for Paris. This famous craft now bore its permanent title; for a few days previously the lovely daughter of the Baron de Bibra, with seven other young ladies and Mr. Green, had stood within the air-inflated vessel, poured a generous libation of wine, and christened the hardy cruiser The Great Balloon of Nassau.

It was in truth a great balloon in various ways; in solidity and strength, in workmanship, in completeness of appointment, in endurance and control. Having accomplished that long journey without a sign of weakness or defect, it was still in prime condition, proudly heading for the farthest verge of Europe. It had not, of course, the instrumental equipment of a modern balloon; but it did possess the elements essential for a long and hard cruise. Since the day of its launching many additions have been added to the art, but these, for the most part, are special adjuncts. The more important features of a good balloon are practically the same to-day as when they were first introduced by Professor Charles and sturdy old Mr. Green.

A still more elaborate and colossal air ship was the Geant, constructed in 1863, for A. Nadar of Paris. It was made of a double layer of white silk, had a volume of 215,000 cubic feet and a buoyancy of 4½ tons. The car was a wicker cabin 13 feet wide by 7 feet high, with a wicker balcony round the top so that the roof could be used as an observation deck—a delightful place to loll in the starlight, or watch the morning sun “flatter the mountain tops with sovereign eye.” The closed car comprised two main rooms with a hallway between them, one containing the captain’s bed and baggage, the other having three superposed berths for passengers. Minor divisions of the car were reserved for provisions, a lavatory, photography and a printing press, the latter to be used for the dissemination of news from the sky, as the navigators floated from state to state. A compensator balloon of 3,500 cubic feet, just below the main bag and connected with it, received the escaping gas during expansion with increase of temperature or altitude, and gave it back on contraction. In fact as well as in name, Nadar’s vessel was a giant. Curiously enough, he called it the “last balloon,” for he expected to realize enough money by exhibiting it, to inaugurate successful flying by means of the helicopter, and thus banish ballooning from the world of futile effort to the domain of bygone dreams and chimæras.

Fig. 11.—Car of Nadar’s Balloon.

The first ascension, made on Sunday, October 4, 1863, was one of magnificent promise. In the midst of a vast holiday throng on the Champ de Mars, the great globe towered aloft nearly two hundred feet, held to earth by one hundred men and twice as many sand bags. In the car were fifteen notable passengers including one lady, the fair young Princess de la Tour d’Auvergne, in morning toilet and a pretty hat. “Lachez tout!” shouts Captain Nadar, the effervescent photographer of Paris. Away they soar, heading for St. Petersburg, with provisions enough to sail beyond the polar sea.

The captain was now in supreme control, with the key to the victual and liquor room in his pocket, and his twelve commandments duly signed by all aboard. They had pledged themselves not to gamble, not to carry inflammable materials, not to smoke unduly, not to throw bottles overboard, not to quit the balloon without permission, but to descend if so ordered, etc. They had sailed at five o’clock in the evening and all was going merrily. But presently trouble came. The valve rope gave way, the vessel was sailing in the dark, and the Godards declared she was drifting to sea, whereas she was drifting in quite the opposite direction. To be on the safe side they threw out the anchors by permission of the commander. One anchor broke, but the other took hold and checked the balloon in spite of the strong wind blowing. At last after three violent bumps on the ground they landed near Meaux at nine o’clock in the evening, one passenger sustaining a broken knee, the others various bruises. It was a grand adventure and all were pleased.

Two weeks later a second voyage was begun in similar style, and again from the Champ de Mars, this time in the presence of the King of France and the young King George of Greece; but now Nadar took along, not the Princess with the pretty hat, but Madame Nadar, his wife. To entertain the crowd before starting, thirty-two persons were first sent aloft 300 feet and drawn back to earth. Finally at five o’clock Sunday evening, October 18th, a party of nine passengers soared proudly northward, well provisioned as before, and eager for a long voyage. They disappeared in the gathering night, leaving their friends much concerned for their safety and ultimate destination. At half past eight they were over Compiegne, seventy-eight miles away, drifting near the ground to say “All goes well” and have the good tidings transmitted to Paris. At nine they crossed the Belgian frontier; at midnight they were over Holland; at sunrise they skirted the Zuyder Zee and entered Hanover; at eight they were coursing headlong toward Nienburg and the North Sea in the current of a swift west wind.

They were now in great peril. If they went to sea they might all be drowned; if they came to earth at such horizontal speed they should be terribly pounded. Choosing the latter evil, they opened the valve and threw down the grappling irons. “To the ropes,” shouted the Godard brothers. Assembling on deck all clung to the suspension ropes to mitigate the shock of landing. Nadar put his arm about his wife to protect her. The anchors snatching a tree, uprooted and dragged it along; then caught and tore off the roof of a house; threshed into a telegraph line pulling down the wires and poles; struck into some firmer obstacle and broke off completely, leaving the huge monster to sweep unchecked in the violent ground current. Owing to trouble with the valve, the gas could not be liberated quickly; the great vessel again and again plunged to earth and rebounded high in air, its ponderous basket crashing through heavy timber, and breaking down whatever opposed its course. For nine miles they pounded over the plain by Nienburg toward the sea, dashing into pools, bogs and thickets, their limbs sprained or broken, their bodies bruised, their faces splashed with mud. Presently through loss of gas the rebounding ceased, the basket dragged along the earth squeezing some of the passengers beneath it, and dumping others out on the ground, leaving them behind. Those remaining tried to assist Madam Nadar to land, but they were tumbled out and she was caught under the basket from which she was extricated with much difficulty, when the balloon was finally halted. Thus their memorable voyage of seventeen hours, covering 750 miles, had a terrific, though not fatal ending. One had a broken femur, another a dislocated thigh, others numerous scratches and contusions. But no complaint was uttered; for the afflictions were regarded as natural concomitants to such interesting sport. After some days tender nursing by the Germans, and solicitous inquiries from the King of Hanover, they returned to Paris; some indeed on their backs, but for all that, none the less admired by their countrymen, as survivors of a marvelous adventure.

Another valiant English leader in aërostation was James Glaisher, member of the British Association for the Advancement of Science. As one of a committee of twelve appointed by that body in 1861, to explore the higher strata of the atmosphere by means of the balloon, he volunteered his services as an observer, when no other capable man could offer to do so. With a professional aëronaut, Mr. Coxwell, and a new balloon specially constructed for the work, cubing 90,000 feet, he made eleven ascensions for the society, four from Wolverhampton, seven from Woolwich. Incidentally he made seventeen other ascents of various altitude; not at the expense of the committee, but as a scientific passenger in public balloon ascents advertised beforehand.

The objects of the enterprise were first to study the physical conditions of the atmosphere; secondly to study the effect of the higher regions upon the passengers themselves, and some pigeons, which they carried along; thirdly to make some observations in acoustics and magnetism, particularly to determine the period of oscillation of a magnet at various altitudes. The specific study of the atmosphere itself was to comprise observations at all altitudes, of the temperature of the air, its pressure, and percentage of moisture; observations of the velocity and direction of the wind, the constitution of the clouds, their height, density and depth, the constitution and electrical properties of the air. They were also to collect samples of the air at different elevations, which later might be examined in the laboratory. Thus the voyages were systematically planned for scientific research, and were the first thorough attempts in England, though similar efforts had been made previously in France. It may be added that Glaisher’s observations were the most important made during the first century of aëronautics, and may be found fully detailed by that hardy investigator himself in the British Association Reports for 1862–66.

Mr. Glaisher’s most interesting voyage of that memorable series occurred on September 5, 1862. Starting from Wolverhampton at three minutes after one o’clock, they soared swiftly upward, passing through a cloud eleven hundred feet thick and emerging in a glorious field of sunlight with an amethystine sky above and a boundless sea of vapor beneath; a sea of rolling hills and mountain chains, with great snow-white masses steaming up from their surface. They had left the noisy bustle of earth in the comfortable temperature of 59°; in three quarters of an hour, they were five miles aloft in a deadly silent atmosphere, two degrees below zero, and approaching one third its usual density, the balloon neck white with hoar frost, the men gasping for breath. Here the observations became increasingly interesting but immensely more difficult. They are graphically told in the following extract from Mr. Glaisher’s classical report:

“I asked Mr. Coxwell to help me to read the instruments, as I experienced a difficulty in seeing. In consequence, however, of the rotatory motion of the balloon, which had continued without ceasing since the earth had been left, the valve-line had become twisted, and he had to leave the car and mount into the ring above to adjust it. At this time I looked at the barometer, and found it to be 10 inches, still decreasing fast; its true reading therefore, was 9¾ inches, implying a height of 29,000 feet. Shortly afterwards I laid my arm upon the table, possessed of its full vigor, and on being desirous of using it, I found it powerless; it must have lost its power momentarily. I tried to move the other arm, and found it powerless also. I then tried to shake myself, and succeeded in shaking my body. I seemed to have no limbs. I then looked at the barometer; whilst doing so my head fell on my left shoulder. I struggled and shook my body again, but could not move my arms. I got my head upright, but for an instant only, when it fell on my right shoulder, and then I fell backwards, my back resting against the side of the car, and my head on its edge; in this position my eyes were directed towards Mr. Coxwell in the ring. When I shook my body I seemed to have full power over the muscles of the back and considerable power over those of the neck, but none over either my arms or my legs; in fact I seemed to have none. As in the case of the arms, all muscular power was lost in an instant from my back and neck. I dimly saw Mr. Coxwell in the ring and endeavored to speak, but could not; when in an instant intense black darkness came, the optic nerve finally lost power suddenly. I was still conscious, with as active a brain as at the present moment whilst writing this. I thought I had been seized with asphyxia, and that I should experience no more, as death would come, unless we speedily descended; other thoughts were actively entering my mind, when I suddenly became unconscious as in going to sleep. I cannot tell anything of the sense of hearing; the perfect stillness and silence of the regions six miles from the earth (and at this time we were between six and seven miles high) is such that no sound reaches the ear.

PLATE I.

GLAISHER AND COXWELL.

PARSEVAL KITE BALLOON.

“My last observation was made at 1 h. and 54 m., at 29,000 feet. I suppose two or three minutes fully were occupied between my eyes becoming insensible to seeing fine divisions, and 1 h. 54 m., and then that two or three minutes more passed till I was insensible; therefore I think this took place at about 1 h. 56 m. or 1 h. and 57 m. Whilst powerless I heard the words, ‘temperature’ and ‘observation,’ and I knew Mr. Coxwell was in the car speaking to me, and endeavoring to arouse me, therefore consciousness and hearing had returned. I then heard him speak more emphatically, but I could not see, speak or move. I heard him again say, ‘Do try—now do.’ Then I saw the instruments dimly, then Mr. Coxwell, and very shortly saw clearly. I rose in my seat and looked round, as though waking from sleep, though not refreshed by sleep, and said to Mr. Coxwell, ‘I have been insensible;’ he said, ‘You have; and I, too, very nearly.’ I then drew up my legs, which had been extended before me, and took a pencil in my hand to begin observations. Mr. Coxwell told me he had lost the use of his hands, which were black, and I poured brandy on them.

“I resumed my observations at 2 h. 7 m., recording the barometer reading at 11.53 inches, and temperature −2°. I suppose three or four minutes were occupied from the time of my hearing the words ‘temperature’ and ‘observation’ till I began to observe; if so, then returning consciousness came at 2 h. and 4 m., and this gives seven minutes for total insensibility. I found the water in the vessel supplying the wet-bulb thermometer, which I had by frequent disturbances kept from freezing, was one solid mass of ice; and it did not all melt until after we had been on the ground some time.

“Mr. Coxwell told me that whilst in the ring he felt it piercingly cold; that hoar-frost was all round the neck of the balloon. On attempting to leave the ring he found his hands frozen, and he had to place his arms on the ring and drop down; that he thought for a moment I had laid back to rest myself; that he spoke to me without eliciting a reply; that he then noticed my legs projected and my arms hung down by my side; that my countenance was serene and placid, without the earnestness and anxiety he had noticed before going into the ring, and then it struck him I was insensible. He wished to approach me, but could not, and he felt insensibility coming over himself; that he became anxious to open the valve, but in consequence of having lost the use of his hands he could not, and ultimately did so by seizing the cord with his teeth and dipping his head two or three times until the balloon took a decided turn downwards. This act is quite characteristic of Mr. Coxwell. I have never yet seen him without a ready means of meeting every difficulty, as it has arisen, with a cool self-possession that has always left my mind perfectly easy, and given me every confidence in his judgment in the management of so large a balloon.

“No inconvenience followed the insensibility; and when we dropped it was in a country where no conveyance of any kind could be obtained, so that I had to walk between seven or eight miles.

“The descent was at first very rapid; we passed downwards three miles in nine minutes; the balloon’s career was then checked, and we finally descended in the center of a large grass-field belonging to Mr. Kersall, at Cold Weston, seven-and-a-half miles from Ludlow.

“I have already said that my last observation was made at a height of 29,000 feet; at this time (1 h. 45 m.) we were ascending at the rate of 1,000 feet per minute; and when I resumed observations we were descending at the rate of 2,000 feet per minute. These two positions must be connected, taking into account the interval of time between, viz. 13 minutes, and on those considerations the balloon must have attained the altitude of 36,000 or 37,000 feet. Again, a very delicate minimum thermometer read—12, and this would give a height of 37,000 feet. Mr. Coxwell, on coming from the ring, noticed that the center of the aneroid barometer, its blue hand, and a rope attached to the car, were all in the same straight line, and this gave a reading of 7 inches, and leads to the same result. Therefore these independent means all lead to about the same elevation, viz. fully SEVEN MILES.

“In this ascent six pigeons were taken up. One was thrown out at the height of three miles, when it extended its wings and dropped as a piece of paper; a second, at four and five miles, and it fell downward as a stone. A fourth was thrown out at four miles on descending. It flew in a circle, and shortly alighted on the top of the balloon. The two remaining pigeons were brought down to the ground. One was found to be dead, and the other, a ‘carrier,’ was still living, but would not leave the hand when I attempted to throw it off, till after a quarter of an hour it began to peck a piece of ribbon which encircled its neck, and was then jerked off the finger, and flew with some vigor toward Wolverhampton. One of the pigeons returned to Wolverhampton on Sunday the 7th, and it is the only one that has been heard of.”

This was the loftiest ascent ever made up to that time; and thus Glaisher, or rather Coxwell, who was in the ring above him, could be called the “highest man” of the first century of aëronautics. Their greatest elevation, however, is now generally estimated at much less than seven miles, and probably below six miles, due allowance being made for inaccuracies of estimate made by Mr. Glaisher. His results, nevertheless, were considered valuable, revealing as they did, that the balloon may be used safely up to the neighborhood of five miles; that the temperature of the atmosphere does not, as previously supposed, decline one degree for each 300 feet of ascent, but often declines more rapidly, and sometimes even increases with the elevation for considerable stretches; that the moisture percentage is extremely slight at an altitude beyond five miles; that at all elevations attainable by man the dry- and wet-bulb thermometers can be used effectively, etc.

A still loftier ascent was made by Professor Berson of Germany, aided by the respiration of oxygen. On July 31, 1901, accompanied by Dr. Süring, he ascended from Berlin in the balloon Preussen to an elevation of 10,800 meters, which at present constitutes the world’s record for altitude. The balloon had a capacity of 300,000 cubic feet, and left the ground two thirds filled with hydrogen, and carrying 8,000 pounds of ballast in the form of sand bags attached to the sides of the basket, so that they could be cut loose with the slightest physical effort.

The Preussen was one of the largest passive balloons ever constructed. In cubic capacity it was comparable with the colossal Montgolfière, La Flesselle, already described, and the huge free balloon Le Geant, constructed by Nadar in 1863. But all were eclipsed by the great balloon of Henri Giffard. This latter measured 450,000 cubic feet, and even to-day ranks as the largest captive balloon ever constructed. It was a familiar object at the Paris Exposition of 1878, where it was installed by the famous inventor Henri Giffard, to give sightseers a bird’s-eye view of Paris. It could take up forty persons at one time, or eight more than once ascended in Nadar’s Geant.

No serious attempt has been made to surpass the altitude flight of Professor Berson and Dr. Süring; for though it is easily possible to carry human beings to a greater height than seven miles, the results seem hardly to justify the cost. To ascend very much higher would require an enormous and costly balloon, and to ensure the comfort of the passenger might require an air-tight car, or armor supplied continuously with fresh air, or oxygen. Such a suit, or car, however, can be made very light, since its pressure must naturally be internal; and it would admit of an extremely rapid change of elevation without discomfort to the passenger. A steel bottle weighing fifty pounds, and filled with compressed air, or oxygen, would supply a passenger several hours, and allow him to breathe under normal pressure. The total weight of a bottle and air-tight car, or suit, need not exceed the weight of a man. Moreover, the ballast could be largely dispensed with, thus admitting of a very rapid ascent from the earth. A celluloid car would have the advantage of transparency, though it might become too brittle at very low temperatures. A suit, or car, with glass portholes would serve in lieu of a celluloid car for transparency. The usual balloon and basket, carrying a steel bottle, furnishing air at normal pressure to a man in a rubberized silk suit is a sufficiently simple and practicable device; the air entering the suit near his mouth and leaving below through a check valve regulated to maintain the desired internal pressure. An air-tight silk fabric capable of enduring safely a tensile stress of 150 pounds per running inch would answer the purposes. But at present there seems to be no incentive to attempt a balloon trip exceeding the heights already attained, unless it be that of notoriety or sentiment.

The French meteorologists have devised a much simpler and cheaper method of exploring the upper atmosphere, by use of small balloons carrying recording instruments. An ordinary silk or gold-beater skin balloon, partly inflated, ascends to a great height with the instruments, drifts away losing gas, and on landing is found by some one who returns it according to written directions accompanying the craft. Another method, introduced by Professor Assman, is to employ closed rubber balloons which at great altitudes burst by the expansion of the hydrogen within them, and allow the instruments to descend in parachutes softly to the ground. Instrument-carrying balloons of the above type are called “sounding balloons,” or balloons sondes, whereas if they carry no instruments, but merely show the course of the wind, they may be called “pilot balloons.” Such sounding balloons have been used to explore the temperature of the atmosphere to an altitude of 18 miles.

In the preceding pages some extended balloon voyages have been described. These were considered very long in their day, but in recent years have been surpassed frequently, first by the professional aëronauts, then by the amateurs and members of various aëronautic clubs practicing aërostation as a sport, and stimulated by attractive prizes. But the man who achieved the longest balloon flight during the first century of the art, seems to have been Mr. John Wise, America’s foremost pioneer balloonist.

Mr. Wise was a rare composite of showman, scientist, sport and dare-devil, who during the four decades succeeding his first ascension at Philadelphia in 1835, made no fewer than 440 voyages. At first the aërial art captivated him by the beauty and sublimity of the natural panoramas witnessed from on high; then he amused himself by dropping things from the basket and hearing them whistle through space; and finally he coquetted with the balloon itself, in various ways to observe the result. On one occasion the neck was choked and the valve could not be operated, so that when the hydrogen expanded with increasing altitude, it overstretched the cover and started a rent in the side of the bag. The balloon descended rapidly, but landed without injurious shock.

The audacious aëronaut then decided to make an ascension and deliberately burst the balloon, by confining the gas in it and throwing out ballast. But first he tried the experiment on a dog, taking him up 4,000 feet, dropping him in a small collapsed balloon and watching him settle slowly to earth. Then rising to an altitude of 13,000 feet he stood debating whether to follow the example of the dog. The balloon quickly ended the question by exploding at the top. The hydrogen rushed out with a tempestuous sound, and the great vessel sank swiftly with a moaning noise of the wind in her rigging. In a few seconds the bag was empty and collapsed on the top of the net thus forming an effective parachute. After an exciting fall of more than two miles, Mr. Wise landed on a farm, with a lively thump, which overturned the basket, and threw him sprawling on the ground. It was fine sport; he decided at once to advertise a repetition of it, and thus was led by degrees to the invention of the ripping panel.[7]

Mr. Wise firmly believed that a steady wind from west to east prevails at a height of two miles. He wished to use this for long voyages, and even contemplated crossing the Atlantic; for he trusted his varnish to hold hydrogen a fortnight if need be. Accordingly in 1873 the New York Daily Graphic paid the cost of a balloon to carry him and two others on that hazardous voyage. The bag had a capacity of 400,000 cubic feet, but was too frail in construction to receive Mr. Wise’s approval, and actually burst during inflation when slightly more than three fourths full. Fortunately, perhaps, for Mr. Wise, he never had an opportunity to attempt the trans-Atlantic voyage; but on one occasion he enjoyed a memorable cruise in the great west wind which so took his fancy. Rising from St. Louis on June 23, 1859, he sailed northeastwardly for twenty hours, and landed at Henderson, N. Y., having traversed a distance of 809 miles, measured directly. But in attempting another long voyage with two companions, in September, 1879, he passed over Lake Michigan, where all were drowned.

In recent years Mr. Wise’s long voyage has been exceeded several times. In 1897 M. Godard sailed from Leipsic to Wilna, a distance of 1,032 miles in 24½ hours; but this was not an official flight nor in a direct course as the crow flies. In October, 1900, M. Balsan voyaged from Vincennes, France, to Rodom, Russia, a distance of 843 miles in 27 hours and 25 minutes, and De la Vaulx starting from the same point landed at Korosticheff, Russia, having traversed 1,193 miles in 35¾ hours. This latter is the longest balloon flight thus far recorded. A close second to this record was made by A. R. Hawley in his spherical balloon America, aided by Augustus Post, in the Gordon Bennett International Balloon Race of 1910. Sailing from St. Louis, October 17th, they drifted 1,172.9 miles from their starting point, and landed in a great forest at Peribonka River, North Lake Chilogoma, Canada, where they were lost for several days.

Fig. 12.—Diagram of a Modern Spherical Balloon with Ripping Panel.

Quite as eventful was the ocean voyage of Walter Wellman, who left Atlantic City October 15, 1910, for Europe in a motor balloon with a drag rope, or equilibrator, voyaged with favorable wind to a point 140 miles northeast of Nantucket Island, then was driven by adverse wind toward Bermuda, and finally rescued by a passing steamer, after 69 hours in the air and a journey of about one thousand miles. A full account of this strange voyage is given in the New York Times of October 19, 1910, and in the Scientific American of subsequent date.

The recent advances in aërostation, though not radically changing the balloon itself, contribute much to its usefulness and convenience. Improvements have occurred in the means of inflation and deflation, in devices for making topographical and meteorological observations, as also for transmitting and receiving signals. Hydrogen shipped in steel tubes is now available for easy and rapid inflation, the process of obtaining it on a large scale making it practically as cheap as illuminating gas. The ripping panel, invented in 1844 by America’s foremost pioneer aëronaut, John Wise, is a simple and an excellent practical device. This is a long patch running longitudinally above the equator[8] of the balloon, feebly sewed to the envelope, and having a cord, called the “ripping cord,” extending down to the car along the outside or inside of the bag, so that the pilot on coming to earth can let out the gas quickly by tearing a rent in the balloon, thus flattening it promptly on the earth’s surface, so as to avoid dragging and bumping if any wind prevails. During an ascension the rise or fall of the vessel may be instantly noted on the dial of the statoscope, the temperature, pressure and moisture of the atmosphere may be read on recording instruments, messages may be sent by telegraph and telephone either by wire or through space, and sky or landscape may be photographed if there be sufficient light. The bag itself has been improved by making it of special fabrics formed of several layers of silk, or cotton, with thin layers of rubber vulcanized between them to render the cloth impermeable, also the bag, when not designed to cleave the wind, is usually given a spherical form which is the figure of greatest volume for a given surface, the figure originally used by the inventor of the gas balloon; but when designed to be tethered in a wind, it is given a longish shape and a tail so that it may ride the wind like a kite. This type of balloon, though first proposed by Douglass Archibald about 1845, was first made a practical invention by Captain von Sigsfeld and Major von Parseval. In a certain sense it is a tethered motor-balloon, just as a kite is a tethered aëroplane.

CHAPTER III

Directly after the first launching of human passengers in a crude aërostat, numerous schemes for controlling the course of a balloon were evolved. Apparently mere flotation afforded less contentment to the early pioneer aëronauts than to the free balloonists of the present hour. Many were eager to apply propelling mechanism to their gas bags, expecting thus to achieve practical locomotion through the air, even a generation before the advent of practical steam navigation. Magnificent dreams they had, indeed, but none the less futile. Few suspected the enormous power required to propel swift balloons of the very best shape and size; still fewer realized the impossibility of driving spherical bags at a practicable velocity.

On the other hand, it must be said, to the credit of that era of investigators, that certain noted scientists, after computing the power required to drive a balloon at high speed, promptly recognized the inadequacy to that task, of any motors then available. In conjunction with favorable aërial currents something might be effected; that they fully grasped; for they knew that the wind frequently has different directions at different levels. They believed, therefore, that by causing the craft to rise or fall to a suitable stratum, by use of various then known devices, it could be made to travel in any direction at the will of the pilot. Likewise they deemed that the rise and fall of a balloon, due to change of buoyancy, could be used to propel it, if sails attached to the vessel were set obliquely to the motion, so as to receive fair pressure; or if the balloon were made flat, or longish, so as to glide horizontally, like a kite or parachute.

Several devices for changing the altitude of the balloon were proposed or tried. If the vessel were a Montgolfière, the mere increase or lessening of the fire would promptly cause it to rise or fall. If a gas bag were employed it could be sent up or down by casting out ballast or opening the valve; or again, as proposed by Pilâtre de Roziere, by having a Montgolfière underneath the gas balloon, and lifting or depressing the whole by altering the intensity of the flame. Finally, an air balloon within a gas balloon was proposed by the Roberts, and a gas balloon within an air balloon was proposed by General Meusnier, in either of which combinations, a change of level could be effected by pumping air into, or letting it escape from, the air bag. All of these devices can be effected and practically operated by a competent balloon maker and pilot; and yet they have not enabled man to realize his dream of navigating the air in all directions without motive power.

The first attempts at balloon propulsion could not be seriously regarded by trained engineers, even at the inception of aëronautics; but still, as infantile steps in the new art, they may deserve passing notice.

Blanchard, on March 2, 1784, made the first real effort to steer a balloon, using for that purpose a spherical gas bag and car provided with aërial oars and a rudder. As he was about to ascend, however, from the Champs de Mars, a young officer with drawn sword persisted in accompanying the pilot, thus compelling Blanchard to leave his wings on earth to allow sufficient buoyancy for himself and his obtrusive guest. His first trial was, therefore, frustrated; but subsequent ones made with that inadequate contrivance also proved futile under the best circumstances; for the scheme was evidently puerile, though tried by various grown-up men besides M. Blanchard.

Fig. 13.—Blanchard’s Dirigible Balloon, 1784.