it may not be necessary to regard it much in selecting the level for the railway, as such road may be made to slope gradually to the requisite level for passing under or over it; but in approaching towns, where many communications are interfered with, it is essential that the railway level should be made higher or lower than the ordinary surface, in order to avoid them. At Liverpool this is effected by tunnels under the town; at the London end of the Birmingham Railway by an open cutting; and at Manchester, Birmingham, and many other places, by an embankment or viaduct. The Greenwich Railway, extending over a metropolitan district the whole of its length, is entirely on a viaduct, and that from London to Blackwall, a similar line, is principally so.

Railways frequently intersect the course of rivers and canals, and numerous bridges are necessary. Where the course of the streams thus crossed is sinuous, expense may sometimes be reduced by making a new channel for the river, such a cut often being the means of avoiding the erection of two bridges, as in the instance of the Manchester and Leeds Railway in the valley of the Calder.

Obtaining an Act of Parliament.—The number of crude and ill-judged speculations brought forward in the years 1835, 1836, and 1837, led to the making of new standing orders, by which the facility of obtaining railway acts is much reduced. Many think that these regulations are now too stringent; and the very limited number of new undertakings sanctioned since they came into operation, though partly to be accounted for by other circumstances, appears to confirm that opinion. The present standing orders of Parliament require the deposit of detailed plans and sections of a proposed line of railway, with certain specified officers in the counties through which it is proposed to carry the railway, in the Private Bill Office, accompanied by books of reference, showing the owner, lessee, and occupier of every house or piece of land likely to be interfered with, long before an application can be made for an act. These plans, &c., are to be deposited, and notices of the intention to apply for an act are to be published in newspapers, at various times in February, March, and April, of the year preceding that in which an act is to be applied for; so that a whole year is allowed for interested parties to consider the scheme, and prepare for opposing or advocating it when before Parliament. Notices must also be given, personally, to all the owners, lessees, or occupiers of property on the line, before a bill is introduced. Before 1837 a period of about six months was required, instead of twelve,-an arrangement far more favourable to railway companies than the present. These preliminary steps are often taken before the formation of a company to carry the project into execution. A company must, however, be formed before a bill can be introduced; and a sum equal to ten per cent. of the estimated cost must be deposited in government securities. After the second reading the bill is referred to a committee, in which the merits of the project, the stability of the shareholders, with other circumstances, undergo a searching investigation. If the bill be opposed in this stage counsel are engaged, and witnesses examined, on both sides, often at an enormous expense. Clauses are often inserted, during the progress of the bill, for the special protection of parties whose property is likely to be injuriously affected by the railway.

A railway act forms the shareholders into a corporate body, and invests them with the necessary powers for the construction of the line. They are authorised to subscribe the estimated amount in shares, and also, usually, to borrow an additional sum equal to one-third of the share-capital, if necessary. The numerous matters embraced in the act frequently extend it to one or two hundred folio pages; and the present arrangements occasion so great an expense when a bill is opposed, that the cost of obtaining an act is often several thousand pounds. The London and Birmingham Railway Company spent more than 72,000%. in obtaining theirs, and the Great Western upwards of 88,000%. The London and Brighton is, perhaps, the most expensive contest of the kind that has taken place,-four or

five companies having engaged in it for two successive sessions : when in committee, the expense of counsel and witnesses in the latter case is stated to have amounted to 10001. daily for about fifty days.

The act of Parliament being obtained, the land required for the railway is set out and purchased. Where exorbitant claims are made for the land, or for compensation for injury caused by the severance of estates, recourse is had to a jury, who generally award a sum far less than that claimed,-frequently less than a quarter.

Formation of the Road.-Under this head is included the execution of those works necessary for the construction of a road (independent of the rails and finishing works) of the required level and width. These works consist of tunnelling, excavation, embankment, and masonry for bridges, viaducts, and other erections. They are commonly divided into convenient portions, and let to contractors under agreement to complete them at a stipulated price and within a specified

time.

Tunnels are, in general, the most formidable works, and the time and expense of forming them can be least accurately calculated. Trials of the nature of the ground are made by boring. Being objectionable also on other accounts, tunnels are avoided as much as possible in the more recently designed railways.

Cuttings or excavations of great depth and extent are of frequent occurrence where the railway passes through high ground. The depth of cuttings is frequently from fifty to seventy feet, and occasionally even greater. One very extensive excavation through the Cowran Hills, on the Newcastle and Carlisle Railway, is a hundred feet deep. The degree of slope necessary in the sides of cuttings varies greatly in different soils. Rock will stand when nearly vertical; chalk varies from nearly vertical to a slope of one horizontal to one vertical, or an angle of 45°; gravel stands usually at one and a half to one; London clay from one to one to three to one, having in some instances stood at the former and slipped at the latter slope. Some materials are insecure at even a greater slope; blue soapy shale having, according to Lecount, slipped at an inclination of four horizontal to one perpendicular. The unexpected slipping of the slopes sometimes occasions much trouble and expense. The great cutting at Blisworth, on the London and Birmingham Railway, is an example of a convenient and economical method of passing through earth in which strata of rock occur. The railway is at a depth of fifty or sixty feet, the upper portion of which is rock, and the lower consists of a less solid material. Instead of making an excavation of the slope required by the lower strata, which would have rendered the removal of the superincumbent rock indispensable, the sides were made nearly vertical, and the rock was supported by an undersetting of masonry. The great breadth of ground occupied by the slopes of cuttings is a serious objection when they are in the vicinity of towns, or pass through valuable property, in which cases the sides may be made nearly vertical, and supported by retaining walls, so curved as to enable them to sustain the pressure of the earth. The extension of the Birmingham Railway to the Euston station at London is a very bold and handsome example of this kind of work. In designing the works of a railway, the amount of excavation and embankment should be balanced as nearly as possible, so as to avoid the necessity of depositing earth from cuttings in spoil-banks, or having to purchase additional land to supply material for the embankments. Attention to this point will sometimes decide which is most expedient, a short tunnel or an open cutting.

Embankments are the artificial ridges of earth formed to support the railway on a higher level than the natural surface of the ground. Their dimensions are often fully commensurate with those of cuttings, from which their materials are mostly procured. In the ordinary mode of proceeding, an embankment is formed simultaneously with a cutting, the earth-waggons proceeding filled from the excavation along a

continuous support of the rails. The most common method of fixing them is to fit them into iron chairs, which are spiked down to blocks of stone imbedded in the ballasting. This plan, although it appears by experiment to afford the firmest foundation, has several disadvantages. The points of support, being isolated from one another, are liable to be deranged by any subsidence in the ground, as well as by the constant vibration consequent upon the rapid passage of heavy trains, and the small but irresistibly powerful action of temperature in causing the expansion and contraction of the rails.

The former of these inconveniences is in some degree obviated by substituting cross sleepers of wood (like those described as being used in the early railways) for the stone blocks upon such parts of the line as are likely to sink. The two rails, being, in this case, attached to the same sleeper, are not liable to be thrown out of gauge, or, in other words, to lose their parallelism, although the unequal sinking of the sleeper may cause one rail to become lower than the other. This application of wooden supports has been in most cases considered a temporary one, it being intended to lay stone blocks in their stead so soon as the ground became sufficiently firm; but it appears from experience, both in this country and in North America, that the motion of carriages on those parts of a line supported by wood is smoother and quieter than on others.

In both of these modes of supporting the rail it is sustained only at intervals of three or four feet, the intervening portion acting as a bridge, which, though very rigid, yields in a slight degree when the heavy locomotive engines pass over it. The surface of the rail is thus converted into a series of minute undulations, the effect of which is to increase the resistance. It has been thought that these undulations were of little consequence, the gain in descending being a counterbalance to the retardation of the ascent; but Professor Barlow, in reporting on experiments made by him in 1835, for the London and Birmingham Railway Company, expresses an opinion that "the advantage of the descent is, owing to the velocity and the shortness of the inclined plane, scarcely appreciable, and that the result of the deflection will be equivalent to the carriage being carried up a plane of half the whole length, the other half being horizontal."

These and some other considerations have led to the adoption of a continuous support to the rail, which has been eflected in several different ways, and with various success. Intermediate supports, being the most extensively employed, will be first noticed; and stone blocks, according to general opinion, claim the precedence among them.

The blocks used upon recently-constructed railways are about two feet square and one thick, though much smaller ones were considered sufficient before the use of locomotive engines became general. They are roughly squared, but have so much of the surface, as is to receive the chair, accurately flattened. The chairs are usually fastened down by two or three iron spikes, to receive which holes are made in the stone, and filled with wooden plugs. The plugs should always be bored to receive the spike, and driven tight into the stone, though they are sometimes put in loose and split by driving the spike. Spikes or pins of well-dried oak have been used instead of iron spikes for securing the chairs, and have been found very durable, but are not generally approved for lines worked at great speed. The introduction of a piece of felt between the chair and the block is useful in deadening concussion. As it is highly important that stone blocks should be well bedded, it is usual to cause them to form a solid foundation for themselves by repeatedly falling from a small elevation upon the spot where they are to rest; sand or very fine gravel being thrown under them between the times of falling. For this purpose a portable machine with an elastic wooden lever about twenty feet long is used, the block, to which the chair has been previously attached, being suspended from the short end, and a man stationed at the opposite end to raise and drop it. When the stone has made a firm bed, and

diagonally, a position now generally preferred, being convenient in repairing the road when a block sinks, because workmen can get at every side for the purpose of ramming ballast under it. Blocks of Scotch asphalte have been tried in lieu of stone, but with what success the writer is not aware. Other similar substances have been suggested in order to diminish expense. It has also been proposed to use cast-iron bed-plates instead of blocks, by which several important advantages were anticipated, but no such plan appears to have been brought extensively into use. In the Dublin and Kings. town Railway an attempt was made to ensure increased solidity by introducing throughgoing stone blocks, which were formed of granite, six feet long, two wide, and one thick, and stretched across the track. These were placed fifteen feet apart; ordinary single blocks being used between them, at intervals of three feet. Owing, perhaps, to the difficulty of bedding such large blocks, the plan did not answer, the motion over them being harsh and unpleasant, and the vibration such as to break many of the long blocks. In some cases, particularly 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 connected with a railway are now almost always Kyanized. 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.

Rails and Chairs.-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. Among other advantages which they possess, the length 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 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. - 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 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 seasoned, 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, South-Western, and other railways.—m and n show another application of a wooden fast

ening, 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 for the purpose 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 ƒ are 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 " 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 cast-iron, 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.

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 North 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; and the application of iron is 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 old 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 agreeable to ride upon, cheaper to maintain, and safer for travelling at high velocities, than a railway constructed in the ordinary manner.

Although some of the supposed advantages are at present questionable, the superior smoothness of motion on such a road, when in good order, is pretty generally admitted; and an opinion seems to be gaining ground, that though longitudinal timber bearings do not produce so firm and unyielding 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 in 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