LONGMANS’ CIVIL ENGINEERING SERIES

RAILWAY CONSTRUCTION

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Frontispiece.][See [p. 97].

KINSUA VIADUCT, ERIE RAILWAY, U.S.A.

LONGMANS’ CIVIL ENGINEERING SERIES

RAILWAY CONSTRUCTION

BY

WILLIAM HEMINGWAY MILLS, M.Inst.C.E.

PAST PRESIDENT OF THE INSTITUTION OF CIVIL ENGINEERS OF IRELAND, AND
ENGINEER-IN-CHIEF OF THE GREAT NORTHERN
RAILWAY OF IRELAND

WITH ILLUSTRATIONS

FOURTH IMPRESSION

LONGMANS, GREEN, AND CO.

39 PATERNOSTER ROW, LONDON
NEW YORK, BOMBAY, AND CALCUTTA
1910

All rights reserved

PREFACE

The construction and maintenance of a railway calls for the application of so many branches of engineering that several volumes would be required to do ample justice to a subject so comprehensive and ever-extending. To avoid attempting so wide a range, the object of the following pages has been to describe briefly some of the recognized leading features which regulate railway construction, and to assist the explanation with sketches of works selected from actual practice.

Where the number of existing good examples is legion, it is somewhat difficult to make a choice for illustration, and the course adopted has been to select such samples of structures as appear best to elucidate in a simple manner the different types of work under consideration.

In the drawings and diagrams many important minor details are necessarily omitted, partly to avoid complexity, but principally to leave more prominent the leading features of the particular piece of work referred to in the description. Some of the sketches of the large span bridges and large span roofs are only shown in outline; but, as their principal dimensions are given, a general idea can be obtained of their actual proportions.

No allusion is made to the requisite strengths of the various structures described, nor to the necessary dimensions of the materials used in their construction, as this would necessitate the introduction of a vast amount of mathematical formulæ which does not come under the province of the object in view, and which the engineer has already at command from his training and works of reference.

Neither is any mention made as to the probable cost of the

different works of construction, as these must always vary to a very large extent, according to the locality, facility of supply, and current prices of materials.

Every railway scheme which is the outcome of public enterprise has its commercial aspect and influence. The large sums to be invested in its construction are expected to yield permanent and increasing returns, and this desirable end can only be attained where there is thorough efficiency in works and equipment, and a full compliance with those national regulations which control matters connected with public safety. The correct dealing with the technical requirements and structural features of the undertaking must always precede all other considerations, as the constituted authorities will exact a proper fulfilment of all the statutory obligations, regardless of the prospective remuneration to the promoters. A stroke of the pen may change a train-service, or alter the rates and tariffs, but a modification in the works of construction arising out of errors or oversight, would entail a heavy expenditure and tedious delay. The essential point of every railway undertaking must be its suitability and completeness in every respect for the duty for which it is intended.

Notes of what has been done are always valuable for consideration and comparison, and that the following brief description and sketches may be found useful for reference, is the earnest wish of the writer.

W. H. MILLS,
M.Inst.C.E.

CONTENTS

[Contents]

CHAPTER I.

Location of a line of railway—Government regulations—Questions for consideration in connection with gauge, gradients, and curves.

Location.—The locating of a line of railway, or the determination of its exact route, is influenced by many circumstances. In a rich country, with thickly populated districts and large industrial enterprises, there are towns to be served, manufacturing centres to be accommodated, and harbours to be brought into connection; while, at the same time, there may be important estates which must be avoided and private properties which must not be entered. Each point will present its own individual claim for consideration when selecting the route which promises the greatest amount of public convenience and commercial success.

In new countries—in our colonies, and especially out in the far west of Canada and the United States—railways have to be laid out in almost uninhabited districts, where there is but little population or commerce to serve, and where the principal object is to obtain the best and most direct route through the vast territories, leaving colonists and settlers to choose afterwards the most convenient sites for towns and villages. Untrammelled by the network of public and private roads and properties which are met with at home, it might appear that the locating of such a line would be comparatively light; but even in such countries, which at first sight seem to present unlimited freedom for selecting a route, much can be done, and should be done, by taking a course through those plains and districts which possess the best natural resources for future agricultural, manufacturing, or mineral development.

In addition to the motives of convenience and policy, the route of every line of railway must be influenced by the natural features of the country—the mountains, valleys, and rivers. These physical obstacles are in some cases on such an enormous

scale as to compel long detours in the formation of a more suitable opening; and in others, although the difficulties are not insurmountable, they may involve works of great magnitude and expense.

In a comparatively rich country, with a prospect of large and remunerative traffic, a succession of heavy works, bridges, and tunnels may be admissible and expedient; but in new countries economy of outlay has to be considered, and costly works avoided as much as possible.

Every one of the heavy works on a line, whether lofty bridges, long viaducts, or costly tunnels, not only enormously increase the original expenditure of the undertaking, but also entail large annual outlay in the necessary constant supervision and maintenance.

Each particular scheme will have to be discussed on its own individual merits. The heavy, high-speed passenger traffic line will suggest light gradients and easy curves, while on secondary lines and in thinly populated districts it may be prudent, for the sake of economy, to introduce sharper curves and heavier gradients. Even in the latter case, and especially in new countries, it is well to keep in view the future possibilities of the undertaking. The steeper the gradients, the greater the cost and time in working the traffic, and if there is every probability of early and large development, the prospective increase may warrant an additional outlay in the original construction.

Large, open plains and wide valleys of important rivers generally afford ample latitude for the selection of a suitable route, and, by taking advantage of the gradations of altitude, a favourable course may be adopted without incurring excessive gradients. When traversing moderately hilly districts, some low ridge or opening may be found, which may form a pass from the one side to the other, and the line may be laid out for a long distance to lead gradually up to the highest point. But when a route has to be laid out over some of those lofty mountain ranges which are met with abroad, the locating of a suitable line, or of any line, becomes particularly intricate and difficult. A comparatively low ridge may be found possessing features in favour of the project, but the question will be how to reach that point. The nearer the summit of these high mountains, the more precipitous the sides; no one slope can

be found sufficiently long and uniform to permit a practical direct ascent, and the only way out of the difficulty is to make a series of detours along the various spurs of the mountains to gain length to overcome the height. Each detour has to be the subject of most careful study. Forming part of a long series of ascending gradients, it has to follow the winding of the mountain-side, must be laid out to be always gaining in height, and will comprise important works, many of them of considerable extent, necessary for protection against the floods and atmospherical changes of the locality.

In these higher altitudes nature is met with on the grandest and most rugged scale. Deep gorges, wide ravines, and almost perpendicular rocks form the pathway along which the line must be carried, and the skill of the engineer is taxed to the utmost to select a course which shall comprise a minimum of the works of magnitude. Mile after mile of line must be laid out in almost inaccessible places, loose or broken rocks must be avoided, a firm foundation must be obtained at all points skirting high ledges, and ample provision must be made for those mountain torrents which rise so suddenly, and are liable to sweep away all before them.

Many grand examples of these detour lines are in existence in different parts of the world, and the traveller passing over them can realize the difficulties that had to be encountered, and the masterly manner in which they have been overcome.

Before proceeding to carry out the works of any line of railway, it is necessary to prepare a complete plan and section of the line, showing the route to be followed and the position of the various curves, gradients, and principal works. Within certain limits, the course of the line may have to be slightly modified as the work proceeds, in consequence of ground turning out unfavourable, river-crossings treacherous, or of sites involving so many contingent alterations that it is found better to avoid them altogether. The route should, however, be so carefully studied out before completing the final plan and section, as to leave only minor deviations of line and level to be dealt with in the actual carrying out of the work.

The promoters of lines in the United Kingdom obtain valuable assistance from the ordnance maps, which give full and reliable information regarding the position of all roads, rivers, and boundaries of counties, parishes, and townlands. In

many parts abroad local maps are scarce, and not always accurate, and engineers have to depend principally on their own surveys, and rely upon the resident local authorities for any particulars as to divisions of territory. On some of our great colonial plains, and out in the far west of America, a line may be laid out for miles without a single landmark to localize it on a plan; but careful setting out, and the relative levels of the ground and gradients, as shown on the section, will always indicate the correct position of any portion of the work.

Both at home and abroad complete plans and sections of any proposed railway must be deposited with the proper Government authorities, and must be approved and sanctioned by them before permission can be obtained to proceed with the works.

The regulations regarding the scale and general arrangement of these plans and sections vary in different countries, and are subject to modification from time to time.

Each country has its own special enactments relative to the method of dealing with roads, rivers, streams, and public and private property proposed to be interfered with in the construction of any line, and a knowledge of these is absolutely necessary for the promoters of any new scheme, inasmuch as some of the requirements may, in certain instances, influence the precise route to be selected.

The English Government has passed several Acts of Parliament setting forth the general conditions which must be complied with in the construction of any railway in the United Kingdom. These conditions, or standing orders, relate both to the acquirement of land and property, the size and description of works for public or private accommodation, and the inspection and official approval of the undertaking when completed. These fixed regulations are alike valuable to the promoters and to the public; the former are informed of the principal points with which the scheme must conform, and the latter know the limit of their legal demands.

No line of railway, or extension of any railway, will obtain Parliamentary sanction unless it can be satisfactorily proved in the outset, that its construction would be of public advantage. This point is of paramount importance, and due weight must be given to it when preparing to refute the evidence of opponents to the scheme.

When conceding the right to make any railway, Parliament grants with it the power to purchase lands or property compulsorily, or by agreement, to change and divert roads and streams in the manner shown on the deposited plans, and to construct all necessary bridges and works in accordance with the standing orders, or such modifications of them as may be approved by the Board of Trade.

The standing orders, or Government regulations, are very comprehensive, and include much detailed information on all questions likely to arise. The following brief summary of some of the principal orders relating to deposited plans, and works of construction, will be found useful for reference.

Extract from Government Standing Orders and Regulations.—All plans and sections relative to proposed new railways must be lodged with the constituted Government Authorities on or before November 30.

Every deposited plan must be drawn to a scale of not less than four inches to a mile, and must describe the centre line, or situation of the work (no alternative line being allowed), and must show all lands, gardens, or buildings within the limits of deviation, each one being numbered with a reference number, and where powers to make lateral deviations are applied for, the limits of such deviation must be marked on the plan.

Unless the whole of such plan be drawn to a scale of not less than 400 feet to an inch, an enlarged plan must be drawn to that scale of every building and garden within the limits of deviation.

The Railway Clauses Act limits the extent of deviation to 100 yards on each side of the centre line in the country, and 10 yards on each side of the centre line in towns or villages.

The distances must be marked on the plan in miles and furlongs from one of the termini.

The radius of every curve not exceeding one mile must be marked on the plan in furlongs and chains.

In tunnels the centre line must be dotted, but no work must be shown as tunnelling, in the making of which it is necessary to cut through, or remove the surface soil. If it is intended to divert or alter any public road, navigable river, canal, or railway, the course and extent of such diversion, etc., shall be marked on the plan.

When a railway is to form a junction with an existing

railway, the course of such existing railway must be shown on the plan for a distance of 800 yards on each side of the proposed junction. In the case of Bills for constructing subways, the plans and sections must indicate the height and width of such subway, and the nature of the approaches by which it is proposed to afford access to such subway.

The Book of Reference must contain the names of all owners, lessees, and occupiers of all lands and houses of every parish within the limits of deviation.

The numbers on the Book of Reference must correspond with the numbers on the plan, and opposite to each number must be entered a brief description of the property, whether field, garden, house, road, railway, or river. It is intended that the plan and Book of Reference together, shall afford ample information to enable all parties interested to ascertain to what extent their property will be affected by the proposed undertaking.

The section must be drawn to the same horizontal scale as the plan, and to a vertical scale of not less than 100 feet to an inch, and must show the level of the ground, the level of the proposed work, the height of every embankment, the depth of every cutting, and a horizontal datum line which shall be referred to some fixed point, near one of the termini.

In every section of a railway, the line of railway marked thereon must correspond with the upper surface of the rails.

Distances on the datum line must be marked in miles and furlongs to correspond with those on the plan; a vertical measure from the datum line to the line of the railway must be marked in feet and decimals at the commencement and termination of the railway, and at each change of gradient, and the rate of inclination between such vertical measures must also be marked.

Wherever the line of railway crosses any public carriage road, navigable river, canal, or railway, the height of the railway over, or depth beneath the surface thereof, and the height and span of every arch by which the railway will be carried over the same, must be marked in figures.

In the case of a public road level crossing, it must be described on the section, and it must also be stated if such level will be unaltered. If any alteration be intended in the level of any canal, public road, or railway which will be crossed by the intended line of railway, the same must be stated on the section and cross-sections to a horizontal scale of not less than 330 feet

to an inch, and a vertical scale of not less than 40 feet to an inch must be added, which must show the present surface of such road, canal, etc., and the intended surface thereof when altered, and the greatest of the present and intended rates of inclination marked in figures, such cross-sections to extend 200 yards on each side of the centre line of railway.

Wherever the height of any embankment, or depth of any cutting, shall exceed 5 feet, the extreme height over or depth beneath the surface of the ground must be marked in figures upon the section.

All tunnels and viaducts must be shown on the section.

At a junction with an existing railway, the gradient of such existing railway must be shown on the section on the same scale as the general section for a distance of 800 yards on each side of the point of junction.

Where the level of any turnpike or public road has to be altered in making any railway, the gradient of any altered road need not be better than the mean inclination of the existing road within a distance of 250 yards of the point of crossing the railway; but where the existing roads have easy gradients, then the gradients of the altered roads, whether carried over, or under, or on the level with the railway, must not be steeper than 1 in 30 for a turnpike road, 1 in 20 for a public carriage road, 1 in 16 for a private or occupation road.

A good and sufficient fence, 4 feet high at least, shall be made on each side of every bridge, and fences 3 feet high on the approaches.

The application to cross any public road on the level must be reported upon by one of the officers of the Board of Trade, and special permission for the work must be embodied in the Act.

Not more than 20 houses of the labouring classes may be purchased in any city or parish in England, Scotland, and Wales, or more than 10 such houses in Ireland, until approval has been obtained to a scheme for building such houses in lieu thereof as the authorities may deem necessary.

Every bridge (unless specially authorized to be otherwise) must conform with the following regulations:— A bridge over a turnpike road must have a clear span of 35 feet on the square between the abutments, with a headway, or height, of 16 feet for a width of 12 feet, as shown on [Fig. 12.]

A bridge over a public road must have a clear span of 25 feet

on the square between the abutments, with a headway of 15 feet for a width of 10 feet, as shown on [Fig. 13].

A bridge over a private or occupation road must have a clear span of 12 feet on the square between the abutments, with a headway of 14 feet for a width of 9 feet, as shown on [Fig. 14].

Road bridges over the railway must have the same clear width between the parapets, measured on the square, as the widths prescribed for road bridges under the railway, or 35 feet for a turnpike road, 25 feet for a public road, and 12 feet for private or occupation road.

It is not compulsory, however, to construct the public road bridges over or under the railway of a greater width than the average available width of the existing roads within 50 yards of the point of crossing the railway, but in no case must a bridge have a less width than 20 feet. Should the narrow roads be widened at any future time, the railway company will be under the obligation to widen the bridges at their own expense to the extent of the statutory widths of 35 feet for a turnpike road, and 25 feet for a public road.

Suitable accommodation works in the form of bridges, level crossings, gates, or other works, must be provided for the owners, or occupiers of lands, or properties intersected or affected by the construction of the railway; or payments may be made by agreement instead of accommodation works. All questions, or differences between the Railway Company, and the owners or occupiers of property affected, will be decided by the authorities duly appointed by the Government for the purpose.

In constructing the railway, the Parliamentary plans and sections may be deviated from to the following extent:—

The centre line may be deviated anywhere within the limits of deviation (100 yards on each side of the centre line in country, and 10 yards each side in towns, or villages).

Curves may be sharpened up to half a mile radius, and further, if authorized by the Board of Trade.

A tunnel may be made instead of a cutting, and a viaduct instead of an embankment, if authorized by the Board of Trade.

The levels may be deviated from to the extent of 5 feet in the country, and 2 feet in a town, or village, and various authorities have power to consent to further deviations.

Gradients may be diminished to any extent, gradients flatter than 1 in 100 may be made steeper to the extent of 10 feet in a

mile, and gradients steeper than 1 in 100 may be made steeper to the extent of 3 feet in a mile, or to such further extent as may be authorized by the Board of Trade.

Suitable fences must be erected on each side of the line, to separate the land taken for the use of the railway from the adjoining lands not taken, and to protect such lands from trespass, or the cattle of the owners, or occupiers thereof from straying on to the railway.

In addition to the Parliamentary plans, and sections, and Book of Reference, an estimate of the cost of each separate line, or branch, must be prepared as near to the following form as circumstances will permit.

[Transcriber's Note: Searchable text of the following form can be found at the [end] of the chapter.]

The same details for each branch, and general summary of total cost.

Every Railway Bill must be read twice, both in the House of Commons and in the House of Lords. A committee, duly appointed for each House, must report upon it, and if the reports from such committees be favourable, the Bill will be read a third time, and passed.

When it has passed both Houses, the Bill receives the Royal Assent, and becomes law.

The minimum scale of four inches to a mile for the plans is so very small that it is rarely, if ever, adopted. It would necessitate enlarged plans of so many portions to show clearly the property or buildings inside the limits of deviation, that in practice it is found expedient to make the plans to a much larger scale.

[Figs. 1] and [2] show a small portion of a Parliamentary plan and section drawn to the minimum scale allowed, with an enlargement of a small part to distinguish the houses clearly.

[Figs. 3] and [4] show a part of the same plan and section drawn to a scale of 400 feet to an inch, a scale which is very frequently adopted, and is sufficiently large to distinguish the buildings and small plots, except in closely populated districts. This scale also gives ample room for reference numbers.

The Parliamentary plans and sections must be accurate in delineation, levels, and description. All property within the prescribed limits of deviation must be clearly shown, and the numbers and description on the plans and book of reference must be concise and complete, to enable the owners to ascertain to what extent they will be affected. In every place where it is proposed to interfere with any public highway, street, footpath, river or canal, the manner of such proposed alteration must be shown and described on both plan and section. The commencement and termination of every tunnel must be correctly indicated, and the length given on both plan and section. An omission of any of the above requirements might prove very detrimental to the scheme, and possibly result in the Bill being thrown out of Parliament for non-compliance with standing orders.

In carrying out the works the constructors have power to deviate the centre line either to the one side or the other, provided that such deviation will permit of the boundary of the works, or property to be acquired, to come within the limits

of deviation or property referenced, and they may also vary the levels of the line to the extent prescribed in the standing orders.

[Figs. 5] and [6] are parts of a Parliamentary plan and section showing alteration of a public road with an overline bridge—also a diversion of a small river to avoid two river bridges.

[Figs. 7] and [8] are parts of a Parliamentary plan and section showing a public road diverted and carried under the railway.

A stipulated time is fixed in the Bill for the purchase of the property and construction of the line, and if this time be exceeded before the completion of the works, it will be necessary to obtain further Parliamentary powers for an extension of time.

Every new railway, or extension of railway, in the United Kingdom, must be inspected, and certified, by one of the inspecting officers of the Board of Trade, previous to Government sanction being granted for its opening as a passenger line.

To facilitate these inspections, and as a guide both to their own inspecting officers and the engineers in charge of the construction, the Board of Trade have issued a list of the principal requirements in connection with all new lines.

The following is a copy of the list so far as relates to works of construction and signals:—

Requirements of the Board of Trade.—1. The requisite apparatus for providing by means of the block telegraph system an adequate interval of space between following trains, and, in the case of junctions, between converging or crossing trains. In the case of single lines worked by one engine under steam (or two or more coupled together) carrying a staff, no such apparatus will be required.

2. Home-signals and distant-signals for each direction to be fixed at stations and junctions, with extra signals for such dock, or bay lines, as are used either for the arrival, or for the departure of trains, and starting-signals for each direction, at all passenger stations which are also block posts. On passenger lines all cross-over roads and all connections for goods, or mineral lines, and sidings to be protected by home and distant signals, and as a rule at all important running junctions a separate distant-signal to be provided in connection with each home-signal.

Signals may be dispensed with on single lines under the following conditions:—

(a) At all stations and siding connections upon a line

worked by one engine only (or two engines coupled together), carrying a staff, and when all points are locked by such staff.

(b) At any intermediate siding connection upon a line worked under the train staff and ticket system, or under the electric staff or tablet system, where the points are locked by the staff or tablet.

(c) At intermediate stations, which are not staff or tablet stations, upon a line worked under the electric staff or tablet system: Sidings, if any, being locked as in (b).

3. The signals at junctions to be on separate posts, or on brackets; and the signals at stations, when there is more than one arm on one side of a post, to be made to apply—the first, or upper arm, to the line on the left, the second arm to the line next in order from the left, and so on; but in cases where the main, or more important line, is not the one on the left, separate signal-posts to be provided, or the arms to be on brackets. Distant-signals to be distinguished by notches cut out of the ends of the arms, and to be controlled by home or starting signals for the same direction when on the same post. A distant-signal arm must not be placed above a home or starting signal arm on the same post for trains going in the same direction.

In the case of sidings, a low short arm and a small signal light, distinguishable from the arms or lights for the passenger lines, may be employed, but in such cases disc signals are, as a rule, preferable.

Every signal arm to be so weighted as to fly to and remain at danger on the breaking at any point of the connection between the arm and the lever working it.

4. On new lines worked independently, the front signal lights to be green for “all right,” and red for “danger;” the back lights (visible only when the signals are at “danger”) to be white.

This requirement not to be obligatory in the case of new lines run over by trains of other companies using a different system of lights.

5. Facing points to be avoided as far as possible, but when they cannot be dispensed with they must be placed as near as practicable to the levers by which they are worked or bolted. The limit of distance from levers working points to be 180 yards in the case of facing points, and 300 yards in the case of trailing points on the main line, or safety points of sidings.

In order to ensure that the points are in their proper position before the signals are lowered, and to prevent the signalman from shifting them while a train is passing over them, all facing points must be fitted with facing-point locks and locking-bars, and with means for detecting any failure in the connections between the signal-cabin and points. The length of the locking-bars to exceed the greatest wheel-base between any two pairs of wheels of the vehicles in use on the line, and the stock rails to be tied to gauge with iron or steel ties. All points, whether facing or trailing, to be worked or bolted by rods, and not by wires, and to be fitted with double connecting-rods.

6. The levers by which points and signals are worked to be interlocked and, as a rule, brought close together, into the position most convenient for the person working them, in a signal-cabin or on a properly constructed stage. The signal-cabin to be commodious, and to be supplied with a clock, and with a separate block instrument for signalling trains on each line of rails. The point-levers and signal-levers to be so placed in the cabin that the signalman when working them shall have the best possible view of the railway, and the cabin itself to be so situated as to enable the signalman to see the arms and the lights of the signals and the working of the points. The back lights of the signal lamps to be made as small as possible, having regard to efficiency, and when the front lights are visible to the signalman in his cabin no back lights to be provided. The fixed lights in the signal-cabin to be screened off, so as not to be mistakable for the signals exhibited to control the running of trains. If, from any unavoidable cause, the arm and light of any signal cannot be seen by the signalman they must, as a rule, be repeated in the cabin.

7. The interlocking to be so arranged that the signalman shall be unable to lower a signal for the approach of a train until after he has set the points in the proper position for it to pass; that it shall not be possible for him to exhibit at the same moment any two signals that can lead to a collision between two trains; and that, after having lowered the signals to allow a train to pass, he shall not be able to move any points connected with, or leading to, the line on which the train is moving. Points also, if possible, to be so interlocked as to avoid the risk of a collision.

Home or starting signals next in advance of trading-points when lowered, to lock such points in either position, unless such locking will unduly interfere with the traffic.

A distant signal must not be capable of being lowered unless the home and starting signals in advance of it have been lowered.

8. Sidings to be so arranged that shunting operations upon them shall cause the least possible obstruction to the passenger lines. Safety-points to be provided upon goods and mineral lines and sidings, at their junctions with passenger lines, with the points closed against the passenger lines and interlocked with the signals.

9. When a junction is situated near to a passenger station, the platforms to be so arranged as to prevent, as far as possible, any necessity for standing trains on the junction.

10. The junctions of all single lines to be, as a rule, formed as double-line junctions.

11. The lines of railway leading to the passenger platforms to be arranged so that the engines shall always be in front of the passenger trains as they arrive at and depart from a station; and so that, in the case of double lines, or of passing places on single lines, each line shall have its own platform. At terminal stations a double line of railway must not end as a single line.

12. Platforms to be continuous, and not less than 6 feet wide for stations of small traffic, nor less than 12 feet wide for important stations. The descents at the ends of the platforms to be by ramps, and not by steps. Pillars for the support of roofs and other fixed works not to be less than 6 feet from the edges of the platforms. The height of the platforms above rail level to be 3 feet, save under exceptional circumstances, and in no case less than 2 feet 6 inches. The edges of the platforms to overhang not less than 12 inches. As little space as possible to be left between the edges of the platforms and those of the footboards on the carriages. Shelter to be provided on every platform, and conveniences where necessary. Names of stations to be shown on boards and on the platform lamps.

13. When stations are placed on, or near a viaduct, or bridge under the railway, a parapet or fence on each side to be provided of sufficient height to prevent passengers, who may by mistake leave the carriages when not at the platform, from falling from the viaduct or bridge in the dark.

14. Footbridges or subways to be provided for passengers to cross the railway at all exchange and other important stations. Staircases or ramps leading to or from platforms to be at no point narrower than at the top, and the available width to be in no case contracted by any erection or fixed obstruction whatever below the top.

At all stations where crowding may be expected, the staircases or ramps to be of ample width, and barriers for regulating the entrance of the crowd at the top to be erected. If in such cases there are gates at the bottom, a speaking-tube or other means of communication between the top and bottom to be provided; and in all cases gates at the bottom of a staircase or ramp to open outwards. For closing the openings at the top, sliding bars or gates are considered best.

The steps of staircases to be never less than 11 inches in the tread, nor more than 7 inches in the rise, and midway landings to be provided where the height exceeds 10 feet.

Efficient handrails to be provided on both staircases and ramps, and in subways where ramps are used the inclination not to exceed 1 in 8.

15. A clock to be provided at every station, in some conspicuous position visible from the platforms.

16. No station to be constructed, and no siding to join a passenger line, on a steeper gradient than 1 in 260, except where it is unavoidable. When the line is double, and the gradient at a station or siding-junction is necessarily steeper than 1 in 260, and when danger is to be apprehended from vehicles running back, a catch-siding with points weighted for the siding, or a throw-off switch, to be provided to intercept runaway vehicles at a distance outside the home-signal for the ascending line, greater than the length of the longest train running upon the line.

Under similar circumstances, when the line is single, provision for averting danger from runaway vehicles to be made—

(1) At a station in one of the following manners:—

(a) A second line to be laid down, a second platform to be constructed, and a catch-siding or throw-off switch to be provided on the ascending line inside the loop-points.

(b) A loop-line to be constructed lower down the incline than the station platform with a similarly placed catch-siding or throw-off switch.

(2) At a siding-junction in one of the following manners, except where it is possible to work the traffic with the engine at the lower end of a goods or mineral train, in which case an undertaking (see No. 35) to do so, given by the company, will be accepted as sufficient:—

(a) A similar loop to be constructed as in the case of a station.

(b) Means to be provided for placing the whole train on sidings clear of the main line before any shunting operations are commenced.

17. Engine-turntables of sufficient diameter to enable the longest engines and tenders in use on the line to be turned without being uncoupled to be erected at terminal stations and at junctions and other places at which the engines require to be turned, except in cases of short lines not exceeding 15 miles in length, where the stations are not at a greater distance than 3 miles apart, and the railway company gives an undertaking (see No. 35) to stop all trains at all stations. Care to be taken to keep all turntables at safe distances from the adjacent lines of rails, so that engines, waggons, or carriages, when being turned, may not foul other lines or endanger the traffic upon them.

18. Cast-iron must not be used for railway under-bridges, except in the form of arched-ribbed girders, where the material is in compression.

In a cast-iron arched bridge, or in the cast-iron girders of an over-bridge, the breaking weight of the girders not to be less than three times the permanent load due to the weight of the superstructure, added to six times the greatest moving load that can be brought upon it.

In a wrought-iron or steel bridge, the greatest load which can be brought upon it, added to the weight of the superstructure, not to produce a greater strain per square inch on any part of the material than five tons where wrought-iron is used, or six tons and a half where steel is used.

The engineer responsible for any steel structure to forward to the Board of Trade a certificate to the effect that the steel employed is either cast-steel, or steel made by some process of fusion, subsequently rolled or hammered, and of a quality possessing considerable toughness and ductility, together with a statement of all the tests to which it has been subjected.

19. In cases where bridges or viaducts are constructed wholly or partially of timber, a sufficient factor of safety, depending on the nature and quality of the timber, to be provided for.

N.B.—The heaviest engines, boiler trucks, or travelling cranes in use on railways afford a measure of the greatest moving loads to which a bridge can be subjected. The above rules apply equally to the main transverse girders and rail-bearers.

20. It is desirable that viaducts should, as far as possible, be wholly constructed of brick or stone, and in such cases they must have parapet walls on each side, not under 4 feet 6 inches in height above the rail level, and not less than 18 inches thick.

Where it is not practicable to construct the viaducts of brick or stone, and iron or steel girders are made use of, it is considered best that in important viaducts the permanent way should be laid between the main girders. In all cases substantial parapets, with a height of not less than 4 feet 6 inches above rail-level must be provided by an addition to the girders, unless the girders themselves are sufficiently high. On important viaducts where the superstructure is of iron, steel, or timber, substantial outside wheel-guards to be fixed above the level of, and as close to the outer rails as possible, but not so as to be liable to be struck by any part of an engine or train running on the rails.

In the construction of the abutments or piers which support the girders of high bridges and viaducts, cast-iron columns of small size must not be used.

In all large structures a wind-pressure of 56 lbs. per square foot to be assumed for the purpose of calculation, which will be based on the rules laid down in the report, dated 30th May, 1881, of the committee appointed by the Board of Trade to consider the question of wind-pressure on railway structures.

21. The upper surfaces of the wooden platforms of bridges and viaducts to be protected from fire.

22. All castings for use in railway structures to be, where practicable, cast in a similar position to that which they are intended to occupy when fixed.

23. The joints of rails to be secured by means of fish-plates, or by some other equally secure fastening. On main lines, and lines where heavy traffic may be worked at high speed, the chairs not to weigh less than 40 lbs.; but on branch lines, or

lines on which the traffic is light, chairs weighing not less than 30 lbs. may be used.

24. When chairs are used to support the rails they must be secured to the sleepers, at least partially, by iron spikes or bolts. With flat-bottomed rails, when there are no chairs, or with bridge rails, the fastenings at the joints, and at some intermediate places, to consist of fang or other through-bolts; and such rails, on curves with radii of 15 chains or less, to be tied to gauge by iron or steel ties at suitable intervals.

25. In any curve where the radius is 10 chains or less, a check-rail to be provided.

26. Diamond-crossings, as a rule, not to be flatter than 1 in 8.

27. No standing work (other than a passenger platform) to be nearer to the side of the widest carriage in use on the line than 2 feet 4 inches, at any point between the level of 2 feet 6 inches above the rails, and the level of the upper parts of the highest carriage doors. This applies to all arches, abutments, piers, supports, girders, tunnels, bridges, roofs, walls, posts, tanks, signals, fences, and other works, and to all projections at the side of a railway constructed to any gauge.

28. The intervals between adjacent lines of rails, where there are two lines only, or between lines of rails and sidings, not to be less than 6 feet. Where additional running lines of rails are alongside the main lines, an interval of not less than 9 feet 6 inches to be provided, if possible, between such additional lines and the main lines.

29. At all level crossings of public roads, the gates to be so constructed that they may be closed either across the railway, or across the road at each side of the crossing, and a lodge, or, in the case of a station, a gatekeeper’s box, to be provided, unless the gates are worked from a signal cabin. The gates must not be capable of being opened at the same time for the road and the railway, and must be so hung as not to admit of being opened outwards towards the road. Stops to be provided to keep the gates in position across the road or railway. Wooden gates are considered preferable to iron gates, and single gates on each side to double gates. Red discs, or targets, must be fixed on the gates, with lamps for night use, and semaphore signals in one or both directions interlocked with the gates, may be required. At all level crossings of public roads or footpaths, a footbridge or a subway may be required.

At occupation and field crossings, the gates must be kept hung so as to open outwards from the line.

30. Sidings connected with the main lines near a public road level crossing to be so placed that shunting may be carried on with as little interference as possible with the level crossing; and, as a rule, the points of the sidings to be not less than 100 yards from the crossing.

31. At public road level crossings in or near populous places, the lower portions of the gates to be either close barred, or covered with wire netting.

32. Mile posts, half-mile, and quarter-mile posts, and gradient-boards to be provided along the line.

33. Tunnels and long viaducts to be in all cases constructed with refuges for the safety of platelayers. On under-bridges without parapets, handrails to be provided. Viaducts of steel, iron, or timber to be provided with manholes or other facilities for inspection.

34. Continuous brakes (in accordance with the Regulation of Railways Act of 1889), complying with the following requirements, to be provided on all trains carrying passengers, viz.—

(1) The brake must be instantaneous in action, and capable of being applied by the engine-driver and guards.

(2) The brake must be self-applying in the event of any failure in the continuity of its action.

(3) The brake must be capable of being applied to every vehicle of the train, whether carrying passengers or not.

(4) The brake must be in regular use in daily working.

(5) The materials of the brake must be of a durable character, and easily maintained and kept in order.

35. Any undertaking furnished by a railway company to be under the seal, and signed by the chairman and secretary of the company.

Recommendations as to the Working of Railways.—1. There should be a brake vehicle, with a guard in it, at or near the tail of every passenger train; this vehicle should be provided with a raised roof and extended sides, glazed to the front and back, and it should be the duty of the guard to keep a constant look-out from it along his train.

2. All passenger carriages should be provided with continuous footboards, extending the whole length of each carriage

and as far as the outer ends of the buffer castings. As passenger carriages pass from one company’s line to another’s, it is essential for the public safety that, although the widths of the carriages on the different lines may differ from each other, the widths across the carriages from the outside of the continuous footboard on one side, to the outside of the continuous footboard on the opposite side, should be identical for the carriages of all railway companies, so that the lines of rails may be laid at the proper distance from the edges of the passenger platforms.

3. There should be efficient means of communication between the guard, or guards, of every passenger train and the engine-driver, and between the passengers and the servants of the company in charge of the train.

4. The tyres of all wheels should be so secured as to prevent them from flying open when they are fractured.

5. The engines employed with passenger trains should be of a steady description, with not less than six wheels, with the centre of gravity in front of the driving-wheels, and with the motions balanced. They should, as a rule, be run chimney in front.

6. Records should be carefully kept of the work performed by the wearing parts of the rolling stock, to afford practical information in regard to them, and to prevent them from being retained in use longer than is desirable.

7. In addition to the block-telegraph instruments, it is desirable that there should be speaking-instruments, or telephones, for communication between signalmen, and books for recording the running of the trains.

8. When drovers or other persons are permitted to travel with goods or cattle trains, suitable vehicles should be provided for their accommodation.

9. It is considered that, in fixed signals, the front lights should show—

Green, for all right;

Red, for danger;

and that back lights, visible only when the signals are at danger, should show white.

10. Refuge sidings should be provided at all main-line stations where slow trains are liable to be shunted for fast trains to pass them. If at such stations it is impossible to

provide refuge sidings, and slow trains have to be shunted from one main line to the other to allow of fast trains passing them, some simple arrangements should be supplied in the signal cabins to help to remind the signalman of the shunted train.

11. Efficient means should be adopted to prevent the accidental opening of the doors of passenger trains.

To carry out the undertaking, the engineer has to prepare working plans and sections to a somewhat larger scale than that adopted for the Government or Parliamentary plans, and on which must be marked the exact positions of the commencement of the curves, straight lines, and gradients. The sites of all the over and under bridges must be shown, and their angles of crossing noted. All road, river, or stream diversions must be indicated, so that the work in connection with them may be laid out on the ground. All culverts and drains must be marked, and their size, depth, and direction described. Public road level-crossings, and farm or occupation-road crossings, must be shown in their proper positions.

The face-lines of the ends of all tunnels should be marked on the working plan and section, and the position of any shafts, which may be intended either for use in carrying on the work or for future ventilation.

A considerable amount of investigation and negotiation will have to be entered into before the locating of the above works can be finally decided. The desire to meet the wishes and convenience of all parties interested must of necessity be controlled by the physical circumstances of each case; very little alteration can be made in the level of the rails, although some variation may be made in their position.

When fixing the depths of culverts and drains, attention must be paid to any probable improvement in the drainage of the district, which might at some future time necessitate the deepening of such of the main culverts where the inverts had been laid too high.

Unless all these details are determined, and shown on the working-plans before the works are commenced, there is the risk that embankments may have to be opened out to admit of bridges and culverts, and cuttings changed to permit of road diversions.

The entire centre-line of railway must be carefully staked

out by driving strong wooden pegs into the ground at the end of every chain length, and along the course of these pegs the longitudinal section must be taken. Three pegs, one on each side of the centre peg, are generally placed at the commencement and termination of the curves. When the longitudinal section has been plotted to scale, and the course of the gradients and level portions worked out and drawn on, then the heights of the ground level and formation level can be marked at each chain, and from them the depths of the cutting and the heights of the embankments can be ascertained and marked at each chain. In addition to the longitudinal section, it will be necessary to take a large number of transverse or cross sections at those pegs, or intermediate points, where the ground is at all side-lying or irregular. These cross-sections are necessary to determine the side-widths, or distances to outer edge of slopes in cuttings or embankments, and also to calculate the actual quantity of earthwork to be executed. For convenience in taking out the quantities, these cross-sections are generally plotted to a natural scale, that is to say, to the same scale horizontal as vertical, as shown in the example of cross-sections, [Figs. 15 to 24]. It is also necessary to obtain information, by boring or otherwise, as to the material of which the cuttings are composed, whether clay, gravel, or rock.

In laying out lines through fairly level plains and populous districts, the absence of great natural obstacles will allow the engineer to carefully consider how far it may be prudent to diverge to the right or to the left, to accommodate towns and places which would be excluded by a more direct through route. There will be ample range for selection, and it will be rather the question of policy than compulsion which will guide him in the route to be taken.

When, however, the locating passes from the lower ground, away up amongst the hills and mountain ranges, it becomes an intricate study whether it will be possible to lay out any line at all which may possess gradients and curves practicable for railway working. The question of property, population, or convenience of access, is here no longer the controlling influence, but in its stead there are the far more formidable natural difficulties to be overcome in working out a trackway to the inevitable summit level. The chief endeavour will be to gain length, and so reduce as much as possible the steepness of the

gradients which at the best must necessarily be severe. In some of the earlier mountain lines constructed abroad the system of zigzags was introduced, as shown in [Fig. 25]. These zigzags were laid out on ruling gradients, one above the other, on the sides of the mountain slopes with pieces of level at the apices, A, B, and C, on which the engine could be changed from one end of the train to the other. Although feasible in principle, the system entailed considerable loss of time in train-working, and was not unattended with risk.

The more modern and simple method of working out the same idea is to connect the main zigzag lines by curves or spirals, thus rendering the route continuous and unbroken. By this arrangement the heavy work and delay in starting or stopping the train at the apices, A, B, and C, as shown on [Fig. 25], is avoided, and the train can proceed continuously on its circuitous journey. [Fig. 26] shows an instance of the zigzags and spirals, as carried out on an important railway abroad. To have made a direct line from D to E, the most difficult part of the route, would have involved a gradient of 1 in 11; but by constructing the spiral course, as shown, the length was more than trebled, and the gradient reduced to 1 in 35.

[Fig. 27] is another example of spiral zigzags in which advantage was taken to cut a short tunnel through a high narrow neck of rock at G, and then by skirting round the hill the line was taken over the top of the tunnel and along the side of the mountain to the summit tunnel at H. By this means the line from F to H was laid out to an average gradient of 1 in 42.

[Fig. 28] shows the Cumbres inclines on the Mexican Railway. The route had to be located through one of the rugged passes of the great Chain of the Andes, whose mountain-sides rise most abruptly from the lower plains, to the great upper-land plateau, some eight thousand feet above sea-level. The ground to be traversed was so steep and difficult that, even with the best available detours and greatest length that could be obtained, the result was an average continuous gradient of 1 in 25 for 12 miles.

[Fig. 29] is a plan of part of the St. Gothard Railway, showing the principal tunnel 9¼ miles long, and some of the adjoining spiral tunnels. The long tunnel through the great Alpine barrier was the only means of forming a railway connection between the two points at Airolo and Goeschenen. Constructed

in a straight line, with easy gradients, falling towards the entrances, efficiency of drainage has been secured, and excessive strain on motive-power avoided. The approaching valleys on each side were in some places too irregular and broken to admit of zigzag loops, and the spiral tunnels were adopted instead. The enlarged plan of two of the spiral tunnels will explain the method of working. An ascending train enters the first tunnel at A, and after passing round almost an entire circle, on a rising gradient, emerges at a much higher level at the point B. Proceeding onward, the train enters the second tunnel at C, and after passing round a similar circle, on a rising gradient, comes out at a still higher point, D, and continues its course up the valley.

The last five sketches illustrate some of the methods which have been adopted when constructing railways through some of the most difficult mountain ranges. They show what has been done, and may serve as guides in working out the location of a line in some hitherto unexplored region.

Gauge.—The gauge of a railway, or its width from inside to inside of rails, affects both its cost and efficiency. If the gauge be exceptionally wide, then the expenditure on works and rolling-stock will be proportionately heavy; and although theoretically the extra wide gauge may possess greater capabilities for accommodation and high-speed travelling, we may find in practice that the necessary requirements may be provided on a much more moderate gauge. On the other hand, if the gauge be exceptionally narrow, there will be diminished convenience both for passengers and merchandise, and a corresponding limit to the speed in transit.

In isolated districts, where passenger traffic is of secondary importance, and where the principal merchandise will be heavy without being bulky, such as mineral ores, slates, etc., a comparative narrow gauge may possibly suit the purpose. For main trunk lines, however, where a large, heavy, and fast passenger traffic will have to be worked, and where goods of all kinds, many of them bulky without being heavy, will have to be carried, an ample gauge must be selected to ensure convenience and safety. A liberal gauge permits the use of commodious rolling-stock without any great amount of lateral overhanging weight outside the wheels; whereas with a narrow gauge there is the tendency—if not the necessity—to use vehicles which

have too great a lateral overhang for proper stability, except at very moderate speeds.

The following list shows the gauges adopted in various countries:—

After many years’ experience of actual working, the broad, 7 feet, gauge of the Great Western Railway has been abandoned for the 4 feet 8½ inch gauge. Doubtless this decision was the result of most careful deliberation, and was made upon convincing proof that the 4 feet 8½ inch gauge could fulfil all the advantages claimed for the wider gauge, whilst at the same time it possessed the merit of less cost of construction and working, and greater facilities for the exchange of traffic with other lines having the standard gauge. The facility of exchange, or through working of rolling-stock, is a leading element of successful railway working, and it is difficult to estimate what would be the amount of loss and delay if we had any great extent of break of gauge on the main trunk lines of our own country.

Although some countries have selected gauges of 5 feet and

5 feet 6 inches, it is interesting to note that the largest number have adopted the English standard gauge of 4 feet 8½ inches, and that the miles of line laid to this gauge far outnumber all the others. The fact that our own home lines, the principal Continental lines, and nearly all that vast network of railways in the United States of America, have been laid to the 4 feet 8½ inch gauge, testifies to the general opinion of its utility and efficiency; and we know that included in that list are the railways which carry the largest, heaviest, and fastest train service in the world.

It would be interesting to trace back, and, if possible, ascertain from whence the exact gauge of 4 feet 8½ inches was derived. No doubt, in the early days of the pioneer iron highways in England, the railways were made the same gauge as the tramroads which they superseded. But why was 4 feet 8½ inches the gauge of the tramroads? We may reasonably infer that the first four-wheeled waggons used on the early tramroads were in reality the same waggons which had been previously used on the common roads for the conveyance of coal and minerals to the ports for shipment, and that the waggons were merely transferred from the roughly paved or macadamised roads to the tramroads. Flanged wheels were then unknown, and the introduction of the tram-plates was at first simply designed to lessen the resistance to haulage. The gauge, or width between the wheels, of these waggons may have been the outcome of long experience as to the most suitable width for convenience of load, stability during transit, or for space occupied on the highway. The width may have been handed down from generation to generation, going back to the time when wheeled vehicles were first built in the country. Perhaps in the beginning the first vehicles may have been imported from Italy, or Greece—countries which in the earlier ages were the most advanced in matters of luxury and convenience.

When in Pompeii, a few years ago, the writer measured the spaces between a large number of the wheel-ruts which are worn deep into the paving-stones in many of the principal streets of that wonderful unearthed city. These paving-stones, very irregular in shape, and many of them 2 feet 6 inches long by 1 foot 6 inches wide, are carefully fitted together, and form a compact massive pavement from curbstone to curbstone. The wheel-tracks, which are in many places worn into the stones

to the depth of an inch or an inch and a half, are always distinct, and there is no difficulty in defining the corresponding track.

The result of a large number of measurements gave an average width of about 4 feet 11 inches from centre to centre of the wheel-tracks, a curious coincidence with the gauge of our own road vehicles at the beginning of the railway era. Whether our selection of the railway gauge of 4 feet 8½ inches has been the result of study, imitation, or caprice, we certainly have the silent testimony of these old deep-worn stones to prove that two thousand years ago the chariots of Pompeii were of very similar gauge to our own of modern times.

Narrow-gauge railways, of gauges varying from 1 foot 10½ inches on the Festiniog Railway, to 3 feet, 3 feet 3 inches (metre), and 3 feet 6 inches, have been made in several places both at home and abroad. Generally speaking, they have been constructed as subsidiary or auxiliary lines in thinly populated districts, with a view to afford some railway accommodation where it was considered that lines of the standard gauge would not pay. In some instances abroad long lines of narrow gauge—3 feet and 3 feet 6 inches—have been constructed as main trunk lines in newly opened out districts. Some of these have since been altered to a wider gauge as the traffic developed, and experience proved that the narrow width of the vehicles was unsuitable for quick transit, or convenience in the accommodation of passengers and goods.

The object in making a line to a narrow gauge is doubtless to save cost in the original construction; but when a scheme for an altered gauge is put forward, it will be well to consider what amount of advantage or saving would be effected by deviating from the standard gauge.

If there be almost a certainty that such proposed line will always remain isolated from all other existing railways of the standard gauge, then perhaps the selection of gauge may be one of minor importance, and there remains but the question whether the description of traffic, and the weights to be carried, can be worked to any greater advantage, or more economically, by deviating from the standard gauge.

If, however, there be a fair probability that such proposed line may at some future time become part of an already established railway system, it would appear to be more prudent to make the line to the standard gauge, and effect economies

by introducing steeper gradients, sharper curves, and lighter permanent way, and keep down working expenses by using lighter locomotives, worked at slower speeds.

High speeds are not expected on narrow gauge railways, and no complaints are made about passenger trains whose highest running speed does not exceed 20 miles per hour. By conceding the same indulgence to light railways made to the standard gauge, great economies might be introduced both in their construction and working. The similarity of gauge would admit the transit of the carriages and waggons of other standard gauge lines, and so avoid all cost and delay in transshipment. The heavy engines could be kept for the main-line working, and light engines for slow speeds would serve for the light standard-gauge lines. As traffic developed, and the train service required heavier and faster trains, the light rails could be removed, and replaced by those of heavier section to correspond to the main line. The similarity of gauge would permit uninterrupted transit of all vehicles to a common centre for repairs, whereas the narrow gauge carriages and waggons, being limited to running only on their own district, must have separate workshops for their repair.

When considering the cost of construction and working of a narrow-gauge railway as compared with one of the standard gauge, there are certain items which are common to both, and in which the narrow gauge could not be expected to obtain any advantage over the standard gauge.

There would not be any saving in getting up the scheme in the first instance;
Nor in the Parliamentary expenses;
Nor in the engineering or carrying out of the works;
Nor in the station accommodation, waiting-rooms, and offices;
Nor in the signals and interlocking arrangements;
Nor in the telegraph;
Nor in the working staff and train men;
Nor in the maintenance of the permanent way, as the same number of men would be required for the inspection and packing of the road, perhaps more.

Little or no saving could be expected in the bridges under the railway, as these must be made to the prescribed widths and heights, irrespective of the gauge of the railways.

Little, if any, saving could be made in river or stream

bridges, as the same amount of waterway would have to be provided in each case.

The same remark applies to culverts and drains.

There would, on the other hand, be a small saving in the quantity of land to be acquired to the extent of a narrow strip or zone, represented by the difference in width between the narrow and standard gauges.

There would also be the same small proportionate saving in the embankments and cuttings to the extent of the difference in gauge.

Also a saving in the overline bridges and road approaches in consequence of less width and height of the opening through those bridges.

And a saving in the rails, sleepers, and ballast of the permanent way, to the extent consistent with efficiency. That some saving may be effected in these is undoubted, but it is necessary to exercise caution, and not rush to the opposite extreme by making the parts too light. A rail should be made not only strong enough to carry well the engines that have to pass over it, but it should also be heavy enough to stand the wear of several years. Narrow-gauge engines must be heavy in conformity with the loads they have to haul. The same amount of power must be exerted to haul a hundred tons on a given gradient, whether the gauge be narrow or broad. In some cases of narrow-gauge railways the original rails, which weighed only 45 lbs. per yard, have since been replaced with others weighing 60 and 65 lbs. per yard. The light 45 lb. rails were evidently not found to be sufficiently heavy to keep the road to proper line and level. The result of our everyday practice seems to prove that there is not only an advantage, but an economy, in adopting rails of a heavy section, and experience would therefore indicate that even for a narrow-gauge railway it may not be expedient to adopt rails weighing less than 65 lbs. per yard.

Gradients.—There are very few localities where the rails on any line of railway can be laid perfectly level or horizontal for more than comparatively short distances. By far the greater portion have to be laid on inclined planes of varying rates of inclination to suit the general formation of the district traversed, and the circumstances of the line to be constructed.

The degree, or rate of inclination, of these inclined planes, or

gradients, may be expressed in various ways. A very general method is to state the number of feet, metres, etc., which can be measured along the gradient before an increased rise or fall of one foot or metre, etc., is obtained. Thus a gradient of 1 in 200 signifies a rise or fall of 1 foot in 200 feet, or 1 metre in 200 metres.

Sometimes the rate of inclination is expressed by stating the number of feet of rise or fall in a mile. In this way a gradient would be described as falling at the rate of 30 feet in a mile, rising at the rate of 20 feet in a mile, etc. Twenty feet to a mile is equal to 1 in 264.

Another method is to give the percentage of rise or fall. In this way the inclination would be expressed as a 1 per cent. gradient, 2 per cent. gradient, ½ per cent. gradient, etc., which for comparison would signify 1 in 100, 1 in 50, and 1 in 200 respectively.

The gradients of a railway most materially influence its facility and cost of working, and every effort should be used to make them as easy as possible consistent with the prospect of the line.

Steep gradients signify heavy locomotives, increased cost of motive-power, reduced speed, and light loads.

The following tabulated memoranda show the approximate loads, exclusive of engine and tender, which can be hauled on the level and on certain inclines at various speeds by engines of the quoted capacities and steam admissions. A medium-sized, ordinary type of passenger and goods engine has been selected for each of the examples. The working of the passenger engine and train is assumed to be under favourable circumstances, with fine weather, fairly straight line, first-class permanent way, modern rolling-stock with oil axle-boxes and perfect lubrication, and all the conditions most suitable to ensure the least resistance to the moving load. For the goods engine and train a greater resistance per ton of load is assumed, as the goods trucks are never so perfect or easy in the running as the passenger carriages. A certain amount of side wind is taken into consideration, and also an allowance for moderately sharp curves, the object being to indicate what may be looked upon as fair, average, workable loads.

The loads for engines of larger or smaller dimensions, or higher or lower pressures, may be obtained by working out the

proportion between the tractive force put down in any of the columns of the tabulated memoranda and the ascertained tractive force of any other engine under the same conditions of cut-off and speed.