KAILKOAD 179 the spring thaws ; in wet weather it must prove very insecure, and in dry weather very dusty. The sleepers soon settle irregularly, placing the rails out of line, and thus are involved rapid wear, deterioration, accidents, and loss to the rolling stock and to the road. The dust rises in clouds, to the great injury of the machinery and of the passenger cars, and seriously incom- moding the passengers themselves. The effects of water about the earthwork of railroads are regarded as so injurious that an eminent Eng- lish authority says : " Wherever it is known or suspected to exist, its immediate source should be traced, and every possible means adopted for diverting it from the slopes and adjacent surfaces." Not only are capacious and permanent culverts, ditches, and drains abundantly provided, but subdrainage by tile drains is also employed to great advantage ; and as a final precaution the road bed is bal- lasted, usually a foot deep beneath the sleepers and another foot around and over them, and for a width on double tracks of 26 ft., the quantity per mile amounting to 10,000 or 12,000 cub. ft. The material preferred for ballast is gravel containing a natural mixture of clean sand, and next to this broken stone in pieces not exceeding 2 in. in diameter. Limestone is not so good as gneiss, as it packs too densely, and trap rock also is likely to become too solid and rigid. A certain elasticity in the bed is essential for the durability of the rails ; and where no other suitable material is at hand, common clay burned in lumps in great heaps intermixed with bituminous coal has been found to answer very well, especially if hard- burned. Cinders and small coal are excellent materials, and in Holland shells and broken bricks are extensively used. The road bed through the long English tunnels, and also upon the viaducts, is well ballasted, and the wear of the rails is thereby materially de- creased. The wooden sleepers on many Euro- pean and some American roads are also pro- tected by some chemical application. (See PRESERVATION OF WOOD.) The ordinary dura- tion of sleepers upon American roads is hard- ly 7 years, but upon English roads it is. 15 years and upward. By the scrupulous atten- tion directed to these details in building the European roads a great saving is effected in the cost of "maintenance of way," engines, and working. Only one half as much fuel is consumed to the mile run on the English and French roads as on those of the north- ern United States ; and the consumption of fuel may be taken as a measure of the resis- tances overcome. If the English trains are from 20 to 30 per cent, lighter than those of American lines, they are run 25 per cent, faster, thus requiring about the same power. The superstructure of railroads is almost universally laid upon transverse wooden sleep- ers, the primary object of which is to give a steady bearing upon the road bed. Seasoned white oak is preferable to any other wood for strength and for holding the spikes. Hem- lock is better than chestnut, and both these are extensively used in the United States. Their dimensions are commonly 8 ft. long with V, 8, or 9 in. width of bearing surface, and their distance apart from centre to centre is from 2 ft. 1 in., as on the Erie road, to 2 ft. 6 in. On the English roads they are com- monly 9 ft. long, 10 in. wide, often squared, and 5 in. thick. They are usually laid 3 ft. apart from centre to centre ; and that a uni- form bearing may be secured, particular care is taken that the sleepers are alike in size and regularly spaced in their beds. In France the experiment has been tried of cutting the sleepers in two in the middle, leaving one in every 10 or 12 ft. to bind the two rails to- gether. The result was very satisfactory, the object being to prevent the spring of the full- length sleepers or the movement they some- times acquire on their centre. But for these and detached rectangular blocks of any mate- rial, either transverse or longitudinal, it is es- sential that the supports should be well packed upon a thoroughly ballasted road bed. In Eng- land and India, where wood is expensive and iron comparatively cheap, rectangular blocks and also inverted pots of cast iron have been tried upon some of the roads, and with good results ; but the conditions of cost are alto- gether unfavorable to the adoption of such devices in the United States. Granite sleep- ers have been tried and have continued in use upon one of the tracks of the Boston and Lowell road. They make a very hard and rigid support, and cannot be used in connection with wooden sleepers interspersed or alterna- ting with them, unevenness in the track soon resulting. The smooth face of a rock ledge has been tried upon the Manchester and Leeds road, the rails being spiked directly down upon it. It was soon found necessary to take them up on account of the excessive wear upon the rails thus placed. The Great Western road in England is constructed with longitudinal bearings or sills measuring 10 in. square, and framed together by cross ties of 6 by 4 in. every 6 ft. The arrangement is said to be easy on the rolling stock, but as regards cost of main- tenance of way this is one of the most expen- sive roads in England. The iron rails, which are generally straight bars of wrought iron, dif- fer greatly in the shape of their cross section, their weight, quality, and the manner in which they are secured to the road bed. Almost the first form was the fish-bellied rail, made about the year 1820. This soon gave place to others of more economical shape, as the T and the i rails, and to these was added the bridge or hollow rail, the form of which is nearly that of the letter U inverted. These have been variously modified in their figures and pro- portions, and a great number of other forms that may not be referred to either of these have been introduced upon different roads. In the United States an inverted T rail has
