78 



H. COX, Esq. ON IMPACT ON ELASTIC BEAMS. 



COMPARISON OF THEORY AND EXPERIMENT. 

 The length of the wire suspending the ball in all cases = 210 inches. 



(Table I. Report on Railway Structures, p. 39.) Statical pressure to maintain 1 inch 

 deflection = 500 lb. Weight of beam 403 lb. 



(Table II. Report, p. 42.) Weight of beam 262 lb. Statical pressure to maintain 

 1 inch deflection 157 lb. 



(Ibid.) Bars half the length of the preceding. Weight of bar 130 lb. Statical pres- 

 sure to maintain 1 inch deflection 1275 lb. 



* In this case the velocities were so great, and the bar was 

 so flexible that the experimental results do not agree accurately 



with those of the formula, which is applicable only when the 

 beam is very rigid. 



