200 MEMOIR OF THE LATE PROF. E. HODGKINSON, F.R.S. 



of bridges and bars of iron are given in the Report of the 

 Commissioners as follows : — 



Ewell Bridge, 



The span is 48 feet ; the statical deflection, produced by 

 the engine and tender 39 tons, and weight of half bridge 

 30 tons, was only '215 inch. This deflection was in- 

 creased to "245 with a speed of 37 miles per hour. A speed 

 of 51 miles per hour produced a deflection of '235. 



Greatest dynamical deflection _ 

 Statical deflection 



14. 



Godstone Bridge. 



The span is 30 feet, the weight of engine and tender 33 

 tons, and weight of half bridge 25 tons ; the statical deflec- 

 tion was '19 inch. This was increased to '25 by a speed 

 of 49 miles per hour. 



The dynamical deflection 



Statical deflection ^ -" 



showing an increase of nearly one-third. 



A pair of steel bars, 2 feet 3 inches by 2 inches broad 

 and J inch deep, gave the following results : — 



Velocity in feet per second 

 Central deflection in inches 



70 



15 



I '02 



14 

 1*32 



29 



1*45 



34 

 i'3o 



44 

 1*03 



A bar of wrought iron 9 feet long, i inch broad, and 3 

 inches deep, with a load of 1778 lbs., gave the following 

 results : — 



Velocity in feet per second 



Central deflection in inches 



•29 



15 



•38 



29 



•50 



36 

 •62 



43 

 46 



In the Commissioners^ Report, Mr. Hodgkinson has 

 given the results of a variety of experiments on the trans- 



