RA IL WA Y CONS TR UCTION. 



193 



Figs. 209 to 272 show sections of rails varying from 72 to 

 60 Ibs. per yard, also a section of a 45-lb. steel flange-rail, much 

 used on 3-foot narrow-guage railways. 



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 Ibs. 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 breaks 

 tend very materially to shorten the life of the rails on the inclines. 



As now made, the steel rails manufactured under the con- 

 verter 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 con- 

 stituents 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 STEBL RAILS WHICH BROKE EITHER IN TESTING 



OB IN LINE. 



