familiar flanged base of the American rail replaced by another head, the object of this design being to enable the rail to be reversed when one head has become worn. These bull-headed rails cannot of course be spiked to the ties, and they therefore require cast-iron chairs for their support. Formerly in America nearly every road used a form of rail peculiar to itself, which differed somewhat in minor dimensions and details from the rails employed by other roads. Recently, however, practice has settled down to the use of a very few standard sections. In America the so-called Am. Soc. C. E. section recommended in 1893 by a special committee appointed by the American Society of Civil Engineers is the one which is most generally used; in Europe the section invented by Mr. Sandberg is chiefly employed. The ordinary length of rails is 30 feet, but rails 33 feet, 45 feet, and 60 feet long are used to some extent. The weight of rails per linear yard varies from 65 pounds, which is the least weight economical for ordinary service, to 100 pounds, which is the heaviest rail actually in use in the United States. Generally for ordinary traffic on roads with easy curves and moderate grades a 70-pound or 75-pound rail is used; for heavy and fast traffic and for sharp curves and steep grades the weights used run from 80 pounds to 85 pounds, 90 pounds, 95 pounds, and 100 pounds. An 80-pound rail of the Am. Soc. C. E. section is 7⅜ inches high, with a head 2½ inches wide and 1½ inches deep, a web 35/64 inches thick and 5 inches deep, and a base 5 inches wide. Of the total weight, 42 per cent. is in the head, 21 per cent. in the web, and 37 per cent. in the base.
ENGLISH BULL-HEAD RAIL AND CHAIR.
STANDARD AM. SOC. C. E. 80-LB. RAIL.
Until 1855 all rails were made of wrought iron, but in that year steel rails were rolled in England, and were laid in track. Steel rails were rolled experimentally in the United States in 1865 and in 1867 they were being rolled to supply orders from the railways. The substitution of steel for iron for railway rails was one of the benefits wrought by the invention of the Bessemer process of steel-making. (See Iron and Steel.) The Bessemer process was introduced and developed in America largely through the efforts of A. L. Holley (q.v.). It has been claimed with substantial justness that no other invention did so much to encourage the development of the heavy-traffic, high-speed American railway as did this epoch-making discovery of Bessemer. In America and England rails are now generally spaced 4 feet 8½ inches apart, this spacing being known as the standard gauge. Various other gauges are employed in other countries, the meter gauge, 39.37 inches, being common in South American countries and Japan, a 5 foot 6 inch gauge being used in India, and a 5 foot 3 inch gauge being used in Ireland. A narrower gauge than the meter gauge has been employed on some railways. The Great Western Railway in England was originally constructed with a 7 foot gauge, and it was not until 1892 that it was converted to a standard-gauge road. A 6-foot gauge was introduced on the Erie Railway and retained long after the standard gauge had become general in the United States. As time passes, however, the 4 foot 8½ inch gauge is becoming more common all over the world. The method of fastening rails to the ties varies. In America hook-headed spikes are almost universally used; the bull-headed rail used in England is wedged into cast-iron chairs which are bolted to the ties; in Europe considerable use is made of bolts; and when steel ties are employed various forms of clamping devices tightened by means of bolts or wedges are used. To allow for expansion, rails are usually laid with a little space between the ends of succeeding rails. The space allowed varies on different roads and with the temperature at the time the rail is laid, but it is seldom more than three-eighths of an inch for the coldest weather and from this distance it gradually decreases to nothing at the maximum prevailing heat for the climate which the road has to endure.
SPIKES FOR FASTENING RAIL TO CROSS-TIE.
ANGLE-BAR RAIL JOINT.
The ends of succeeding rails are clamped together by various devices going under the general name of rail joints. The simplest form of rail joint is the fish plate, and the most common form is the angle bar. (See Fish Plate.) The joint remains the weakest point of the rail despite all the efforts which have been made to remedy this weakness. It may be noted in passing that these efforts are responsible for the numerous forms of patented rail joints which are on the market, several of which have met with substantial success. Rail joints are defined as suspended when the opening between the rail ends comes over the space between the adjacent ties, and as supported joints when this opening comes over the
