140 TRANSACTIONS OF THE [fEB. 1, 



wheels. Between the trucks and in front of the pilot of the lo- 

 comotive there will be decided elevations of the rail and rever- 

 sion of the fibre stresses. 



If the track is in good surface, it may not be noticed b}' the 

 eye that the depressions under the wheels for the entire length 

 of rail are not uniform, but as a rule one can readily see that the 

 wheels, as they roll over the rails, rise and fall, more or less, ac- 

 cording to the stiffness of the rails, their smoothness and condi- 

 tion of the track. 



That the surface of the rails would be uneven to the wheels 

 was recognized almost as soon as the construction of railroads 

 began, and in this country the cars were mounted upon trucks 

 with springs so that the wheels could follow the undulations in 

 the rails, while the centre of gravity of the car would not follow 

 so undulating a line. 



I have never found this theory discussed in the reports of the 

 earlier civil engineers, but I have no doubt it was considered 

 by some of them. 



The earlier civil engineers were constantly trying to reduce 

 the undulations in the tracks to the lowest possible limits, as 

 the}^ recognized and acted upon the principle that the less the 

 undulations in the track the less the resistance to the trains, and 

 the less xAie cost of maintenance. 



The substitution of Bessemer steel rails for iron, about 1865, 

 produced so much smoother tracks, and the rails wore so 

 much longer, that in a few years the cost of transportation per 

 ton was cut down from about two cents to one cent per mile. 



The Bessemer steel rails gave a great impetus to railway build- 

 ing, and there followed a large reduction in the rates, to meet 

 which, larger rolling stock was introduced, and it became neces- 

 sary to again reduce tiie undulations in the tracks so as to cut 

 down the cost of transportation and maintenance. 



Having made mechanism to measure the resistance of trains, 

 and having found that on smooth track, well maintained, the re- 

 sistance was less than on a poorer track, several railroad presi- 

 dents wished me to make some mechanism which, by running 

 over the track, would show its condition, and the nature of the 

 undulations, to see if they could not be reduced. 



I made several pieces of mechanism some 3-ears ago, and 

 have used them practically in their present form since 1881. 



In 1884, I described the mechanism before the New York 

 Academy of Sciences, and the results then obtained. 



The more extended introduction in recent years of stiffer rails 

 has caused results to be realized in the track, which a few years 

 ago were not considered possibilities, and in order that those pres- 



