278 On the Resilie7ice of Materials ; with Experiments, 



the height that broke the pieces vvhicli would admit of a second 

 trial, are here repeated. 



Those trials made with the same piece are marked with the 

 same letter. And the same weight of seven pounds was used in 

 all the trials. 



Observations. 



III. From the preceding table it appears that the height is not 

 directly as the length, as We find a shorter length actually requires 

 more height than a longer one ; and it is to this difference chiefly 

 that I am desirous of drawing the attention of those who have 

 more leisure to make experiments, and more ability to pursue the 

 investigation. The difficulties which attend making experin)ents 

 on the laws of percussion are well-known, and various means have 

 been devised to avoid the irregularities which occur in sucli ex- 

 periments, but with little success. 



These irregularities evidently originate in the methods of mea- 

 suring the effects ; at least, it is more probable than that there 

 is any defect in the theory of falling bodies. Camus, who pub- 

 lished a considerable number of experiments on the effects of per- 

 cussive forces, fottnd that the nature of the bodies struck, and of 

 the supports on which they rested, had much influonce on the 

 effects. Also in o;her experiments, made for the purpose of as- 

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