Page:The American Cyclopædia (1879) Volume XIV.djvu/192

 180 RAILROAD been in very general use, so as to be known as the American rail. It has a broad bearing base, and is easily secured to the sleepers by hook-headed spikes driven into elongated slots in the edge of the flange, or merely over the edge, thus allowing expansion and contraction of the rail with changing temperatures with- out disturbing the fastenings. With this rail the cast-iron chairs employed for seating and holding almost all other rails were at first used to strengthen the joints. Up to about the year 1854 the weight of rails had been steadily increasing from about 35 Ibs. per lineal yard till it had reached 85 and in some cases even 100 Ibs. No advantage was found in the very heavy rails, however, but on the contrary the iron in such large piles was necessarily less worked in the manufacture and was in a poor condition for wear. The ten- dency has since been to return to lighter rails, of 55 to 65 Ibs. to the yard, and to require these to be made of iron originally good, the piles to be first rolled into blooms, and these to be again brought to a welding heat, and then rolled into rails. The miserable qual- ity of much of the iron on American roads is due to the deficient working, the fibres of the iron as it wears showing that they had never been thoroughly incorporated togeth- er. In bargaining for it no test and no par- ticular conditions of manufacture were re- quired, as is customary in other countries. Rails of 45 Ibs. have worn under the heaviest traffic for 20 years, us those laid in 1837 on the Reading railroad, while others of nearly double the weight have given out on other roads in one, two, or three years. The first rails employed on the Stonington railroad, of 54 Ibs. to the yard, also lasted 20 years. Rails have gradually increased in length to 15, 16, 18, and 20 ft., and even 30 ft., which latter is now the common length made by American rolling mills and used upon American railroads. An important feature in the rail is its height or depth. Its stiffness, if the rail could be re- garded as a rectangular beam, increases as the square of the depth ; thus doubling the height and retaining the same weight of material quad- ruples the stiffness, but doubling the height and weight also increases its stiffness eight times. The effect of a want of stiffness in the rail is deflection between the supports under the weight and a mashing of the iron into the wood of the sleepers, which continually in- creases the mischief. Even between rigid sup- ports the temporary depression of the rail is such as to present a continual ascending plane in front of the wheels, which the descent of the slope from behind does not in any measure compensate, the advantage of this being wholly balanced by other considerations. In 1857 steel rails were first rolled in England, and so greatly were they found to surpass iron rails in endurance, that, notwithstanding their greater cost, the demand for them kept ahead of the capacity of the mills to make them, till Besse- mer's process of producing them from the puddling furnace reduced their cost and greatly increased the demand for them. At first steel rails were used only at such points as were sub- jected to extraordinary usage, as at terminal stations and for switches, frogs, and crossings. They were gradually introduced by the roads having the heaviest traffic, and finally they have come to be used in the first construction of many of the more important new roads, and by nearly all the old ones instead of the iron rails as they wear out. The following figures show the sections of rails now commonly in use in America and England. Various devices Sections of Rails. have been invented and used from time to time in securing rails to the sleepers, and for keep- ing their ends together. All of them recognize the effects of expansion and contraction of the rails under the action of the weather, and in laying rails a proper allowance, varying with the length of the rail and the variations of temperature, is always made for this. By neglect of this precaution the rails heated by the sun have sometimes expanded so as to bo thrust upward, lifting the sleepers one or two feet out of the ground. From this cause, a train running in June, 1856, on the North- eastern railway in England, at 40 m. an hour, was thrown off the inside of a curve, though the 82 Ib. rail was fastened every three feet in heavy chairs and " fiahed " at the joints. Almost the universal fastenings in England used to be cast-iron chairs, made to hold the rail in an opening in the top, into which it was seated and keyed by a wooden Wedge. The chairs were themselves strongly bolted down upon the sleepers. Those for receiv- ing the two ends of adjoining rails were much heavier and stronger than the others, weighing from 26 to 89 Ibs., and others 18 to 26 Ibs. It is of great consequence to keep the ends of the rails securely upon the same hori- zontal line. If one end is depressed by the weight coming upon it, the wheel strikes the end of the next rail with a concussion that soon shatters the rail, and being repeated at other joints seriously injures the rolling stock. Various methods of keying and fastening the ends of the rails have been used, but they have generally been discarded in favor of what is known as the fish joint, first tried in 1843 at New Castle, Del., but not finally adopted to any extent till 1847. This method was not favorably received on American roads at first, owing to the difficulty of applying it to the low rails generally in use, but in some form or other it has finally superseded all others everywhere. As first proposed, two sleepers were to be placed 6 in. apart at the joints, and