ON THE ENDURANCE OF METALS. 

 Series No 1 — continiu'd. 



Xo. of Kevolutious tress per square inch Factor a 



4:65 



' Factor a ' is the ratio of the ultimate tensile strength per square inch 

 of the specimen to the calculated stress upon the outside fibres, due to 

 the load on the end of the projecting bar. ' Factor h ' is the ratio of the 

 static load required to bend the bar a moderate amount beyond the elastic 

 limit, to the load actually imposed upon the revolving bar. These defi- 

 nitions will be made more clear in further references to the table. 



The above series includes a representative number of the experi- 

 ments with rotating spindles. As a rule, the spindles were 1 inch 

 diameter, and projected about 10 inches from the end of the revolving 

 shaft in which they were fixed. A speed of between fifty and sixty 

 revolutions per minute was maintained day and night. The ' soft steel ' 

 was fine rivet steel, having a tensile strength of from 60,000 lbs. to 

 64,000 lbs. per square inch, and an elongation of 28 per cent, in 8 inches. 

 The ' hard steel ' was a high-class ' drift ' steel, having a tensile strength 

 double the above, and an elongation of one half the extent. The ' iron ' 

 was the best rivet iron, having a tensile strength of from 58,000 lbs. to 

 61,000 lbs., and an elongation of 20 per cent. 



Series Xo. 2. 



The above series is a selection from the experiments with flat bArs 



r F 2 



