120 



would be of the same nature as that produced by elasticity 

 in the clamp, but obviously many times as large. If the 

 error produced by one thick leather washer be but 10 inches 

 of reduced height, surely the effect of the elasticity of the 

 clamp will fall well within the limits of error in these expe- 

 riments. 



The effect of cold on the breaking of the wire was tried 

 thus — the clamp and the lower extremity of the wire were 

 cooled by means of ether spray, and the weight dropped as 

 before. The effect of cooling the wire near the clamp was 

 in all cases to make the wire break more easily, in some 

 cases very markedly so. A similar result would follow 

 under similar circumstances from the formula for the 



resilience J-gr ; and it is the almost universal experience 



of those who have to handle crane chains and lifting tackle 

 that these are most liable to breakage in cold weather. To 

 this efiect of temperature and to the variable quality of 

 wire even in the same coil I attribute the discrepancy 

 between the various observations. 



The first column gives the height of fall observed, the 

 second the reduced height, and the third the point at which 

 the wire broke. The observations marked * are those in 

 which cold was applied. The two series were tried on 

 different days about a fortnight apart and on wire from 

 different parts of the same coil. In all cases the upper 

 clamp rested on the bare boards of the floor above. 



FIRST SERIES. 



161bs. weight. 



Inches. Inches. Point of Rupture. 



72 60 18'' from top. 



78 65 12'' from bottom. 



78 65 24" from top. 



81 67|- at top and bottom, 



82 68J 21" from top. 



84 70 ,.. at bottom. 



84 70 at bottom. 



*48 40 did not break. 



*54 45 at bottom. 



*60 50 at bottom. 



*72 60 at bottom. 



