TENSILE STRENGTH OF RIVET IRON. 



415 



Experiments on the Tensile Strength of Rivet Iron. 



At the time when the preceding experiments were instituted, it was con- 

 sidered expedient to make them on plates of ordinary quality, and of the de- 

 scription in general use. For this purpose Staffordshire plates were selected, 

 as being of medium quality, such as arc employed in the construction of boilers, 

 ship-building, &c. Plates of a higher character, such as the Lowmoor and 

 double-worked (\ndX\\\es, might have been selected ; but those most in demand, 

 and which are manufactured in large quantities, Avere considered more de- 

 sirable, although it left untouched a question of some importance in regard 

 to the influence of heat upon the finer qualities, generally known as " scrap " 

 and "faffotted" iron. This description of iron is forged from old iron scrap, 

 and rolled into bars for bolts and rivets. It is a fine ductile iron of great 

 tenacity, and works freely under the hammer; and it was determined to apply 

 to it the same experimental tests as had been applied to the Staffordshire 

 plates. 



From the results of these experiments, it will be seen that they indicate 

 precisely the same law as was found to influence the Staffordshire plates, 

 the maximum strength being at a temperature of 325°, rather higher than 

 that indicated by the plates. This is irrespective of the superior strength of 

 the bar iron as compared with that of the plates. 



Having prepared the lever, as before, a long bar, |-ths of an inch in 

 diameter, was selected and cut into lengths, which were then reduced to the 

 form shown in the 

 annexed sketch, 

 with shoulders to 



receive the shackle. The specimens, when immersed in the bath, were drawn 

 asunder by the same process as that described for the plates. 



Experiments to ascertain the Influence of Temperature on the 

 Tensile Strength of Rivet Iron. 



Table XVII — Area of section ='24'S50. 



From the above it will be observed that the strength of the best quality of 

 bar iron greatly exceeds that of the plates, being in this experiment two- 

 fifths more, and in some experiments, at higher temperatures, nearly double 

 that of the Staffordshire plates. 



