502 



Prof. B. Hopkinson. 



[Jan. 31, 



effects in the same material of impulsive and of long continued stress. 

 The nature of the material, however, sufficiently appears from the static 

 tests. 



Iron Wire. This was bought as iron wire, No. 10 gauge. Its 

 diameter was 0*1275 inch. After placing it in the chase it was heated 

 to redness and stretched, to straighten it. The annealing softened it 

 materially, and somewhat unequally in different parts. 



FIG. 2. 



The following was a set of observations on this wire, which is 

 typical : 



Steady tension 50 Ibs. Height of fall 5 feet. 



Contact point 20 inches from the upper end. 



One division on micrometer head = 1/2000 inch = 1 /40000th part. 



Micrometer reads 34-5 with a steady load of 50 Ibs. when contact 

 first made on the spring being pushed up. 



