EXPLANATIONS OF PLATE X. 



Fig. I. — Representation of the continuous curve showing how the 

 metal of the rail is stressed under the wheel loads of a train. 



Fig. 2. — Wheel loads and wheel base of Boston and Albany Passen- 

 ger Locomotive, No. 209, on 95 -lb. rails ; showing deflection of 

 rail and depression of the ties, ballast and road-bed under the wheel 

 loads. 



Fig. 3. — Stremmatograph records, enlarged 21^ times. The first 



made under fast trains, the tremors and vibrations in the rails be- 



> 



ing very decided. The records on the bronze plates are more dis- 

 tinct than in the reproduction. The upper record was from loco- 

 motive No. 888 and 5 ^^'agner Palace cars ; the lower record was 

 from locomotive No. 889 and 7 cars. 



(110) 



