Valuable and interesting statistics have from time to time been recorded, with a view to ascertain the average life of a steel rail, by obtaining the number of million tons of train load which it would sustain before it became worn down to such an extent as to be no longer of service on the line. It will be readily understood that the rate of wear of a steel rail will depend not only on the weight and section of the rail itself, but on the class of rolling-stock, and the description of traffic it has to carry. It will also be largely affected by the circumstances of whether the line is on a level or on an incline. The writer has had careful measurement taken of the wear of the steel flange-rail (Fig. 265), 79 lbs. per yard, and the result shows that with a traffic not exceeding twenty-four goods and passenger trains per day, one-tenth of an inch was worn off the top of the rail in ten years on the comparatively level portions of the line; but that the same amount of one-tenth of an inch was worn off in six years by the same traffic, on the same district of the line, in places where the gradients varied from 1 in 100 to 1 in 70. The heavy pounding of the engines, and the working of the brakes tend very materially to shorten the life of the rails on the inclines. As now made, the steel rails manufactured under the converter process exhibit great similarity in the analysis of their component parts; at the same time it is well known that a slight preponderance or reduction of one or more of the constituents will result in making the steel hard or soft. The following statement gives the analysis of twelve steel rails, six of which were classed as _hard_ steel, and six as _soft_ steel:-- HARD STEEL.--ANALYSIS OF SIX STEEL RAILS WHICH BROKE EITHER IN TESTING OR IN LINE. -----------+--------+--------+--------+--------+---------+--------- | 1. | 2. | 3. | 4. | 5. | 6. -----------+--------+--------+--------+--------+---------+--------- Carbon | 0·47 | 0·51 | 0·56 | 0·43 | 0·47 | 0·54 Silicon | 0·09 | 0·08 | 0·08 | 0·09 | 0·095 | 0·121 Sulphur | 0·06 | 0·06 | 0·06 | 0·06 | 0·054 | 0·056 Phosphorus | 0·07 | 0·06 | 0·06 | 0·08 | 0·08 | 0·057 Manganese | 1·23 | 1·10 | 0·90 | 1·23 | 1·15 | 1·26 Iron | 98·08 | 98·19 | 98·34 | 98·11 | 98·151 | 97·966 +--------+--------+--------+--------+---------+--------- | 100·00 | 100·00 | 100·00 | 100·00 | 100·000 | 100·000 -----------+--------+--------+--------+--------+---------+--------- SOFT STEEL.--ANALYSIS OF SIX STEEL RAILS WHICH STOOD THE TEST WELL, 194 AND BENT FREELY WITHOUT SHOWING ANY SIGN OF FRACTURE.