272 THE SCIENTIFIC PAPERS OF 



punching a number of holes through a rail the strength of that 

 rail was diminished to less than one-fourth, as measured by a 

 falling weight ; and this fact should lead to the preference being 

 given to a mode of fastening in which no such holes were made. 

 It was true that in ordinary use no such working strain as the 

 weight of a ton falling through a number of feet was put upon a 

 rail ; but engineers liked to err upon the right side in a question 

 of safety, and were justified, he thought, in giving the preference 

 to steel rails of mild or ductile quality ; for if the steel was not of 

 tough quality, there was danger of its being hardened by acci- 

 dental exposure to cold during manufacture. Steel containing 

 more than fV P er cent, of carbon would become very brittle if by 

 accident it was thrown into water when red hot ; and such a rail 

 might break with a very slight shock. In France it was the habit 

 to make steel rails containing ^ per cent, of carbon, and as far as 

 wearing qualities were concerned French engineers were right ; 

 but there was some danger in using such rails, particularly if the 

 continuity of the rail was broken by holes. Therefore he did not 

 agree with the author in his assertion that the test by blows was 

 altogether inadmissible : he thought it a desirable test to apply 

 along with others. The particular test which the author proposed 

 was valuable in so far as it proved the fair wearing quality of the 

 material ; but he did not consider it sufficient as a test for the 

 wearing quality of rails under the most trying circumstances. 

 Mr. Bramwell had pointed out one of the reasons why it was not 

 sufficient, inasmuch as it did not provide for the propelling action 

 of the driving-wheels on the rail. But, he might have added, it 

 did not provide for the sliding action of the wheels. Upon inclines 

 the wear and tear of rails was much greater than on a level road ; 

 and that was owing, not to any increase of weight, but to the 

 different mode in which that weight passed along the surface of 

 the rails. If the load merely rolled over the surface, the effect 

 upon the rails was very different to what it was if the same weight 

 slid over it, burnishing or trying to dislodge every particle from 

 its neighbour. The machine therefore appeared to him to be 

 incomplete, unless some means of testing that sliding action upon 

 the rail were provided in addition to the rolling action. If 

 stopping the rotation of the wheels would not lead to the expendi- 

 ture of too much power, it would provide a means of subjecting 



