RAILWAY.

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extent.* It should not he of so light a nature as to produce dust, or to he easilyraised by the current produced by passing trains, or by wind, and so get into theworking parts of the engine or the axle-boxes of the carriages, and also incommodetravellers. When broken stone can be obtained, it may be considered to form thebest ballast, provided a few inches of gravel or very small stone be laid between itand the timber.

3rdly. The smoothness of the joints of the rails, to effect which care should be takenthat the rails are square-butted and well seated on the chairs or longitudinal timbers,and so fixed that in expanding and contracting from the effects of temperature, theintervals between the rails shall not much vary: these intervals are often increasedin the case of transverse sleepers by the effect of the traffic passing always in onedirection and drawing the rail in the direction of motion. The perfection of apermanent way is for every part to be alike in solidity and smoothness; and for thispurpose the attention of the Engineer should be especially directed to the joints,which are naturally the weakest points in the rails. When railways were first com-menced, machinery not being so perfect as it is at present, it was found impracticableto obtain rails of sufficient weight of greater lengths than 15 or 16 feet; but byimprovements in the process of manufacture they may now be procured of nearlydouble that length. It is therefore advisable, in determining the rails for a railway,to ascertain to what lengths rails of the required weight can be rolled, and to adoptthose of the greatest length, even at an increased cost, as the joints or weak partsdecrease in the ratio of the length of each rail, and there is a corresponding reductionin the means to be applied to stiffen the joints, and in the labour necessary to main-tain them. In the comparison of the two systems, it should not be omitted that thecontinuous bearing has a decided superiority over the ordinary transverse sleeper road,by dispensing with the cast-iron chairs, which often break, with the oak keys usedto fasten the rail in the chair: these keys, by the effect of the atmosphere (dampexpanding and dry hot weather contracting them), are constantly varying even in thesame day from tight to loose, and vice versa, and are acted upon by the frictionof the rail, which, in expanding, contracting, and deflecting, tends to move them, sothat they are a constant source of anxiety, and require to be examined daily at leastonce, and, where there is a night traffic, twice. It is a very common thing for thekey of the joint chair to work clear of the joint, and so leave the rail at that pointwithout lateral support, which must be highly dangerous to passing trains. To ob-viate the evil arising from this, it has been proposed to lay a flat bar of iron, extendingbetween the chairs on each side the joint, in the chairs and touching the side of therail, the oak key securing it in its place.

* The following rates may be assumed as the approximate cost of ballasting in this country:

Average per cubic yard.8. d.

Excavating, carrying, depositing, and spreading material for ballast, . from

Is. 6d. to 3s, 2

If obtained from the necessary excavation of permanent cutting, and paid foronce as earthwork, and with a lead not exceeding half a mile, . . .20

Broken stones or coarse ballast,.from Is. 6d. to 3s. 2 2£

Burnt clay,. from 2s. 6c?. to 4s. 6c?. 3 6

Gravel or other fine ballast,.from Is. 2d. to 2s. 1 7

If obtained from side cuttings or elsewhere, and not otherwise paid for as earthwork:

Broken stone for coarse ballast, ...... from 2s. to 3s. 2 6

Burnt clay,.from 3s. to 4s. 6<f. 3 9

Gravel or other fine ballast,.from Is. 6d. to 2s. 6d. 2 O'

If the lead exceeds half a mile, addition to the prices named, according to the

increase of distance for any fractional part of a mile, at the rate per mile of

from 4 d. to 8 d. 0 5$