1897.] NEW YORK ACADEMY OF SCIENCES. 141 



ent here to-night may better understand the results, I will in a 

 few words describe the main features of my track indicator. 



1. There is a special car fifty-eight feet long, weighing 72,000 

 pounds, and under one end there is arranged a special six wheel 

 truck of eleven foot wheel base, each wheel being ground true 

 and cylindrical. The two outer pairs of wheels of the truck roll- 

 ing on the rails serve as a reference plane, while the undulations 

 of the rails for the length of the wheel base cause vertical move- 

 ments of the middle pair of wheels which are transmitted for 

 each rail to a moving band of paper and recorded. 



By means of universal joints and slides in the shafts, any ver- 

 tical movement of the body of the truck or car is not communi- 

 cated to the pens. The wheel load of 6,500 pounds for each 

 wheel has been kept constant from the first use of tlie truck, and 

 the positive wheel base has enabled me to repeat the diagrams 

 year after year over the same track and to obtain comparative 

 results, showing whether the track was or was not improving. 



The recording mechanism passes from a continuous band 

 of paper twenty inches wide, 8.8 feet per mile, or one inch 

 of paper for each fifty feet of track. On this moving band of 

 paper are mechanically recorded the surface undulations of each 

 line of rails, their side irregularities, gauge of track, rolling^mo- 

 tion of the car, elevation of the outer rails on curves, and side 

 and vertical shocks to the car. 



Other pieces of auxiliary mechanism on the truck or about 

 the car perform their functions mechanically, but record elec- 

 trically through a battery- of nine or more, electro magnetic pens, 

 as required. 



The special mechanisms for recording the total undulations of 

 the rails in feet and inches, one for each line of rails, are in- 

 dispensable, for they sum up from the smallest fraction of an 

 inch to the largest of the undulations, as the car runs over the 

 track, doing what would be impossible by manual labor. The 

 discs and shafts are ground with the greatest possible accuracy, 

 and though each mechanism must be large and strong, it is as 

 delicately constructed as a watch. 



The figures given by these form the basis for the condensed 

 diagrams. The results obtained by the summing up mechanism 

 have exceeded all expectations, and are independent of personal 

 opinion. 



The markers for ejecting paint on the rails where deflections 

 exceed a given amount have been of great service to the track- 

 men, pointing out where deflections occurred in the rails long 

 before they would be detected by the eye. The markers are 

 carried upon auxiliarj' frames, attached to the outer journal 



