on sharp curves, iron tie-rods have been used to connect two
opposite chairs, and counteract any tendency to separate
which might arise in such situations from the isolation of
the blocks.
The use of cross-sleepers, which are represented by cc,
Fig. 13, needs little remark. They are mostly from seven to
nine feet long, and consist sometimes of whole trunks of
small size, and in other cases of half trunks laid with the
flat or sawn side downwards. These and other timbers con-
nected with a railway are now almost always Kyanized, and
the durability imparted to them by that process is greatly in
favour of their use as a permanent foundation. Several
lines of railway have recently been laid entirely upon these
sleepers.

The distance between the points of support varies from three to five feet. Bearings of greater length have been used, but on railways for locomotive engines have been found unsuitable, from their greater liability to get out of repair. Experience has not fully decided the comparative advantages of long bearings with heavy rails and blocks, and short ones with comparatively light supports; but a greater length than three feet nine inches or four feet has seldom proved successful. Owing to the deflection of the rails, Professor Barlow enforces the importance of placing the supports exactly opposite to each other, that both sides of a carriage may be equally affected.

|

side of the rail. Each pin has a slit through it, which, when in its proper position, tallies with holes through the cheeks of the chair. Iron keys driven into these holes prevent the pin from moving, and, acting as wedges against the end of the slit, force the pin tight against the rail. The chair represented is a joint chair, and g shows the form of the joint, which is called a half-lap. The narrow part of the rail is not divided, but turned aside at the joint, as shown by the dotted lines. Intermediate chairs are similar, but have a pin on one side only. This mode of fixing allows the rail to slide a little in the chair, on account of expansion and contraction, and the keys are not so liable to work loose as when in contact with the rail. These are all for fish-bellied, and the following for parallel rails.-h is a rail and chair invented by Mr. Daglish, and rewarded by the London and Birmingham Railway Company, as presenting the best sectional form of rail. The chair is proposed to be fixed to the block or sleeper by bolts passed through from the under side, and keyed above the chair. The rail is fastened by two semicircular iron keys driven in opposite directions. This arrangement, though ingenious, has the disadvantage that the rail could not be taken up without removing the chair.-i is a contrivance in which an iron ball, dropped into a socket in the chair, is forced against the rail by a key driven through a hole in one cheek of the chair. It is simple, and affords sufficient lateral movement for the effect of temperature on the rail. This form of rail is known as the T rail.-k and o are a section and ground-plan of a chair in which the rail is held by a wooden key. The keys are well sea-oned, and when in use become by expansion almost immoveable; because, as shown in o, they are most compressed in the centre. So great indeed is the expansive force of the wood, that it occasionally breaks the chairs. This mode of construction is extensively used on the Grand Junction, Birmingham, Southampton, and other railways adopted by Mr. Storey on the Great North of England railway. A block of wood is so placed in the chair as to be prevented from moving endways, and is held to the rail by an iron wedge driven through the cheek of the chair.- is a rail contrived with the idea of fitting the wheel more accurately than those of the ordinary shape, but it is not much used. The rails here represented vary much in strength; a and b were made about thirty-five pounds to the yard, but have been found too light, and replaced by parallel rails of sixty pounds; e and fare fifty-pound rails, for three feet bearings. Rails similar to k are made from sixty to seventy-five pounds per yard or more, for bearings of three to five feet, and they are now seldom used of less weight than seventy pounds to the yard. The most common joints are square, as n and o, but half-lapped and scarfed or diagonal joints are also used. The concussion produced by a very slight irregularity at these points is so injurious, that probably increased care and expense in making them perfect would be well bestowed. Chairs are almost invariably made of castiron, as their complex form renders it difficult to manufacture them otherwise with sufficient economy; but as they are liable to breakage from their brittleness, it has been proposed to make them of malleable iron, and machinery for the purpose has been patented, but apparently not yet brought into operation.

Rails and Chairs.-Allusion has been made in a previous page to the difference between fish-bellied rails, or those with the under side curved so as to give increased depth in the centre of the bridge between two chairs, and those of a parallel form, which are of the same depth and section throughout. The experiments of Barlow and others leave it questionable whether any additional strength is obtained from a given weight of iron by the fish-bellied shape, and therefore parallel rails are now almost universally adopted. They possess this, among other advantages, that the length-m and n show another application of a wooden fastening, of bearing on the different sides of a curved track may be so varied as to keep the chairs opposite to one another, which cannot be done with fish-bellied rails. Fig. 14 represents some of the principal varieties of form and contrivances for fixing the rails, which have been introduced on English railways: a is a section of the fish-bellied rail originally Fig. 14.

used on the Liverpool and Manchester railway, the shaded part being that which enters the chair, and the outline indicating the increased depth in the centre.-b is the same rail, as fixed in the chair, the black part representing the end of an iron wedge or key, which is driven in to secure it. -c and d are a section and side view of a plan invented by Mr. Losh, and used on the Newcastle and Carlisle railway. The rails are made with a curved projection on the under side, to fit into a suitable concavity in the chair, as indicated by the dotted lines in d. Two iron keys are used, driven in opposite directions. Any contraction of the rail tends to draw it laterally out of the chair; but in doing so, the curved base rises in its seat and tightens the keys, which press downwards as well as sideways.-e and fare similar views of a method contrived by Robert Stephenson, and used on part of the London and Birmingham railway. In this the seat of the rail is flat, but bears upon a segmental piece of iron laid loose in a concavity in the chair, so that an irregularity which may cause the chair to tilt in the direction of the rail, may not affect its position. The rails are secured by cylindrical pins, the points of which enter depressions in the

Railways on Continuous Bearings.-The introduction of this kind of railway is perhaps mainly to be attributed to the extensive use of timber in such works in America. It has not only been used in lieu of stone, but also in a great measure in the place of iron. In many of the American and Some of the Continental railroads, beams of timber laid continuously, and firmly connected together by cross pieces, are made to supply the strength usually given to iron rails; the application of iron being limited to a flat bar or plate two inches and a half wide, and from half an inch to an inch thick, nailed to the beams on their inner edges for the wheels to roll upon. Though differing in details, this construction of railway is very like the oldest form used in this country, the wooden tramway. Frequently these beams or wooden rails are supported upon cross-sleepers; but whether they are so or not, their breadth of surface causes them to receive considerable support from the ballast or road materials, along their whole length. Mr. I. K Brunel, engineer of the Great Western railway, was one of the first British engineers who proposed a similar construction, which he did with the hope of obtaining a smoother and more elastic road, which should at once be more agree able to ride upon, cheaper to maintain, and safer for travel

ling at high velocities than a railway constructed in the ordinary manner.

on

Although some of the supposed advantages are at present questionable, the superior smoothness of motion such a road, whet. in good order, is pretty generally admitted, and an opirion seems to be gaining ground that, though longitudinal timber bearings do not produce so firm and unvielding a railway as stone blocks, and may therefore require rather more power in working, this disadvantage is more than counterbalanced by the diminished wear and tear, of which the comparative absence of noise is a tolerably accurate criterion. The Great Western railway can hardly be compared with any other, on account of its increased width, but the London and Croydon, which is entirely, and the Manchester and Bolton, Hull and Selby, and several other lines, which are partially laid in this manner, and which in other respects resemble those of the more common construction, may be fairly brought into comparison with them. The Greenwich railway is a remarkable instance of the superior comfort of timber bearings to those of stone, the rigidity of the latter being aggravated by the circumstance of being on a viaduct. On this line, as has been the case on that from Dublin to Kingstown, it has been deemed advisable to remove the blocks, and substitute a more elastic structure of wood. The longitudinal timbers on the Croydon railway vary from nine to fourteen inches wide, and four and a half to seven inches deep; and cross sleepers are bolted under them at intervals of three feet. The rails are of the form shown at p, Fig. 15, and are screwed down at intervals of eighteen inches on each side, a layer of felt being interposed between them and the timbers. These rails weigh about forty-seven pounds to the yard.-q, Fig. 15, is the rail of the Great Western railway, which is fixed | Fig. 15.

in a similar manner, but the screws on the inner side of the rail are round-headed and countersunk, while the others are ordinary square-headed bolts. The longitudinal timbers are of larger dimensions, and the cross-pieces or transoms are placed fifteen feet apart, and framed with them, their office being more to keep the track in gauge than to bear any considerable part of the weight.- and s are forms of rail sometimes used on continuous bearings, r being fastened by clamps or pins driven in obliquely. Rails similar to p have been fixed in the same manner, but the use of screws, though expensive, is decidedly preferable.

Continuous bearings of stone have been tried, but found too harsh and rigid; and some ingenious combinations of wood or iron with natural or artificial stone or burnt clay, have been proposed, but not hitherto brought much into

use.

Gauge, Width between Tracks, &c.-The gauge or width between the two rails forming a track is one of the points in railway practice which has excited much discussion. On the old railways it was of little consequence, provided a good horsepath could be ensured without interfering with the rails. Four feet was not an uncommon width, but many lines were less. Some of the colliery railways in Northumberland are four feet eight inches and a half, and from these the Stockton and Darlington, Liverpool and Manchester, and other lines, took their gauge. The advantage of uniformity has led most companies to follow this example, and for a time it was rendered imperative by parliament, but at present no standard is fixed by the legislature. The ordinary width being considered inconveniently limited, Brunel fixed upon seven feet as the gauge of the Great Western and its tributary lines. Much opposition has been made to this bold step, mainly on account of the inconvenience of not being able to connect with other lines, which is in some degree obviated by laying an inner rail for the use of narrow carriages on any portion of railway passed over by two companies whose lines are laid of different widths. The superiority of this enlarged gauge is apparent in the increased power and speed of the engines, and the stability and convenience of the carriages; but mary who admit the inconvenience of the narrow gauge consider seven feet to be beyond the most advantageous width. Six feet two inches has been recommended by the Irish Railway Commissioners. Six feet is the width of some of the continental lines; the Dundee

and Arbroath, and Arbroath and Forfar railways are five feet six inches; and the Eastern Counties, and London and Blackwall, about five feet. The ordinary standard in America is four feet eight inches and a half, having been copied from the Liverpool line. Several recent lines in this country have been made four feet nine inches, to allow rather more play to the flanges than the common width. One of the great recommendations of a wide gauge is the scope that it allows for improvements in machinery, a circumstance evidently of much importance when it is considered that the experience of ten years only has led to the enlargement of locomotive engines to so great a degree that their weight and cost are now nearly treble what they were when the Liverpool and Manchester railway was opened. The principal argument on the other side is that by increasing the width and bulk of carriages atmospheric resistance would become more formidable; but Dr. Lardner's experiments lead to the conclusion that this resistance is not affected by the mere front of a train so much as to render this objection very important.

The width between the two tracks is a matter of much less consequence, as it has little effect except in limiting the width of load that may be carried. On the Liverpool and Manchester line it is four feet eight inches and a half, which is convenient as allowing waggons to run on it during the construction of the road. The London and Birmingham railway and many others have a space of six feet, which allows loads of ten feet wide to be carried with safety. The same intermediate space on the Great Western railway, in consequence of the increased gauge, allows a maximum load of twelve feet. The space necessary outside the tracks is dependent on the width of load provided for, and seldom exceeds four feet, except on embankments, where a little more is sometimes allowed, so that in case of carriages getting off the track, there may be width for them to run on the ballasting until the inner wheels come in contact with the outer rail, which will in most cases prevent the train from overturning.

In laying the rails, allowance should be made for the effect of temperature, which will cause a difference of length in a fifteen-feet rail, exposed to a range of 76° Fahrenheit, of about 4th of an inch. From want of attention to the temperature when the rails are laid, too much allowance is frequently made, which, especially with square joints, causes an unnecessary shock to the carriages. The insertion of a piece of wood between the ends of two rails is an ingenious mode of avoiding concussion from this cause, the wood expanding as the iron contracts.

In the description of fig. 8, it is stated that the wheeltires are made slightly conical, in order that the flanges may come in contact with the rails as little as possible. In ordinary wheels three inches and a half wide, the inclination of the tire is about 1 in 7, the diameter at the outside being an inch less than close to the flange. The wheels are so fixed that when running straight the flanges are about an inch from the rails. When the rails are fixed vertically, the line of contact between them and the wheels is, in consequence of their conical shape, so narrow as to cause considerable wear. Most engineers therefore give a slight inclination inwards to the rails, that they may present a greater surface to the wheels, although the friction is increased by the rubbing of the conical tire. This inclination is stated by Lecount to be of an inch in eleven inches, or about 1 in 29, on the Birmingham railway; on the Great Western it is 1 in 20.

In running on a straight road, the conical tires keep the carriage in the true line of direction, because any deviation from it causes the wheels on one side to roll on an increased and those on the other on a reduced periphery, an irregularity which immediately checks itself. But on a curved track the centrifugal force overcomes that of gravity so far as to cause the flange on the outer side of the curve to approach the rail, and consequently the opposite wheels to roll on unequal peripheries, thereby voiding part of the friction consequent on the wheels (which are fixed to the axle) being compelled to revolve with equal velocity, though the outer one has to pass over a greater length of rail than the other. To prevent unnecessary friction between the flange and the rail, it is usual to lay the outer rail on curves rather higher than the inner one, that the opposing forces may be so balanced as to cause average loads moving at the medium speed employed to pass round the curve without the flanges on either side coming in con

Contrivances for conducting engines and carriages from
Fig. 18 is designed to illustrate the manner in which
one track to another are required in a variety of situations.
They generally consist of switches and turntables, so modi-switches are applied at passing-places and crossings. a b is

the kind first described are used at the points a and b, and, | instant, which would require much more power than sufas they have always to be passed through in the same order, fices, when they are started, to keep the whole in motion. they are made self-acting, that at a being held by springs Various contrivances, more or less complete and effective, in the position for guiding carriages on to the lower track, are in use for this purpose, but fig. 20 may serve to give a and being opened by the flanges of the engine-wheels for correct idea of the principles on which they all act. It rethe passage of the trains in the contrary direction, while presents the ground-plan of a passenger-carriage, the body that at bin like manner conducts trains passing towards a being removed. The frame, which is outside the wheels, is into the upper track. This kind of passing-place has been supported on lapped springs, which, by brass bushes or successfully used on the Newcastle and Carlisle and other bearings, rest on the ends of the axles, they being extended railways. cd represents another arrangement for the same beyond the wheels, and accurately turned, for that purpose. purpose, which may have the same kind of switch, but is aa aa are buffers, or discs of wood or metal, sometimes cogenerally used without any, the impetus of the train always keeping it to the straight track, while, if suitable openings Fig. 20. be made for the flanges, it cannot escape from the rails in running from the double into the single part. ef shows the arrangement of a crossing on a railway with two tracks, switches being placed at both junctions, which, being only for occasional use, are worked by hand, men being stationed at gg for the purpose. Owing to the accidents which occur when switches in such situations, or at the junction of two main lines of railway, are neglected or misplaced, plans have been proposed, but not brought into use, for placing them under the command of the engineer of an approaching train, who cannot be absent from his post. It is usual to affix a signal apparatus to them, which, by displaying a coloured disk of wood or stretched canvass to the enginedriver, informs him of the position of the switches as he approaches them, and affords an opportunity of checking his speed if they are wrong.

At the points where two rails cross, grooves are formed to allow the flanges to pass; and, to check any tendency in the wheels to escape from the rails, guard-rails, as indicated in Fig. 18, are fixed within the track, to guide the inside of the flanges.

Turn-tables are useful in transferring single carriages from one track to another, which they do in much less space than any arrangement of crossings and switches. They consist of circular platforms of iron and wood, fixed on a level with the tracks, and mounted on friction-wheels, so as to turn on their centres with great facility. Fig. 19 repreFig. 19.

a

C

sents two turn-tables so laid as to communicate with one another. Four rails are laid across each, and made to tally precisely with those of the track. If it be desired to transfer a carriage from the track a to that marked b, it is rolled on the turn-table at d, and then, the catches which held the turn-table steady being released, the platform, with the carriage upon it, is turned a quarter round. The carriage is then rolled on the turn-table e, and being again turned a quarter of a circle, is in a right position for running on the track b. Carriages may in like manner be transferred to a cross-track, as at c. Locomotive-engine houses are frequently made octagonal, with eight radiating tracks, the engines being moved to or from any of them by means of a large turn-table in the centre. That at Camden Town has

sixteen tracks connected in this manner.

Carriages.-Railway carriages for the conveyance of passengers are usually very capacious, the bodies being made to project over the wheels, which on ordinary lines seldom exceed three feet diameter. This arrangement is not productive of danger, since the evenness of a railway, the comparatively low build of the carriages, and the great weight of the iron wheels, axles, and framing under the body, prevent the liability of overturning. On account of the rapid speed at which they travel, and the violent shocks to which they are occasionally subject, great strength of construction is necessary; and the circumstance of several vehicles being linked together in one train renders the use of an elastic apparatus for starting and stopping them essential, both for the safety and comfort of passengers, and the protection of the vehicles themselves. Elasticity in the traction is also necessary, in order that the engine may not have to overcome the inertia of the whole train at the same

vered with cushions, fixed on the ends of long rods which pass through the frame and along the sides to the ends of the long springs cc, which are capable of moving towards each other when pushed by the rods, but are prevented by stops on the frame from moving in the opposite direction. The centre being allowed to slide backwards and forwards, both springs are brought into action by an impulse given to either end. All the buffers in a train being placed at the same height and width, they come into contact when the carriages run towards one another in stopping suddenly, and the jerk is by them communicated to the springs cc, whose elasticity allows so much motion as to prevent any injurious shock to the carriage. The traction apparatus, or that by which the carriages are drawn forward, consists of rods passing through the frame at bb', and connected in a manner which it is unnecessary to describe, with the small springs e'e, which also act together, the centre of e pressing against the cross-bar of the carriage-frame as an abutment, when the pull is from b, and that of e', in the like manner, when the traction is in the direction of b'. The connection between the different carriages often consists of a jointed bar of iron, which is disconnected, when necessary, by the removal of a pin. Chains are sometimes used, and occasionally united by a peculiar kind of screw, which draws the carriages so close that their buffers come in contact. In some carriages the same springs serve both for traction and buffing, and spiral or helical springs are not unfrequently applied to the purpose. Axle-guides, fixed to the framing, are used to keep the axles square; but a more elastic construction of carriage, in which the axles have sufficient play to enable them to adapt themselves to a curved track, and the springs for bearing the weight, drawing, and buffing, are made of an unusually light character, is being introduced by Mr. Adams, with great promise of success. Many engineers appear to be of opinion that the construction of carriages, as well as of the railroad itself, has hitherto been too rigid, and Mr. Adams conceives that the adoption of his bow-springs, and other improvements, will at once increase the comfort and safety of railway conveyance, and diminish the wear and tear, which, with the present heavy and comparatively inelastic carriages, is very great. The ordinary first-class carriages convey eighteen passengers, having a treble body, with six seats in each compartment; and the second-class, of similar make, carry twenty-four passengers. Those on the Great Western railway, which are mostly on six wheels, are much larger, some of the second class vehicles seating seventy-two persons. The wide gauge allows the use of bodies so large that some are fitted up as elegant saloons. A splendid carriage, about twenty-eight feet long and nine wide, has been recently prepared for the use of Her Majesty and suite, when travelling on this line. Open carriages, in which the passengers stand, are frequently used for short stages. Waggons for goods and cattle, trucks for the conveyance of stage-coaches and private carriages, and horse-boxes, are all mounted on springs, but their buffing-apparatus is often very simple and inelastic. The weight of the ordinary passenger-coaches, when empty. is mostly from three to five tons.

Locomotive Engines.-In the rapidly extended applica