286 Messrs. J. H. Gray and J. B. Henderson. 



This shows a diminution of density of ^ per cent. 



Effect of Drawing through Holes in a Steel Plate. 



Copper Wire. A ; length of the same copper wire as was used 

 before, diameter 2 mm., was drawn, without any special care, through 

 twenty holes of uniformly diminishing diameters, the density being 

 measured after drawing through every third hole. Table I gives the 

 results obtained. It will be seen that, whereas in stretching the 

 density was diminished, in drawing it is considerably increased. 

 There would seem to be a maximum after drawing through twelve 

 holes, but as the wire became very difficult to draw by this time, and 

 broke after being put through six more holes, the subsequent decrease 

 in density may have been due to flaws in the metal, caused by the 

 rough treatment which it had received. The ultimate diameter was 

 1-3 mm. 



Table 1. 



Density. 



Before drawing 8'85 



After drawing through three holes 8*87 



,, ,, more holes. . . . 8'92 



,, ,, ,,.... o'yo 



.... 9'005 



,, ,, 8'94 



8 .09 



*i*KR*JI " " 



Manganese-Copper. A length of this alloy (10 per cent, manganese, 

 90 per cent, copper), diameter 1*2 mm., was drawn through several 

 holes, till the diameter was reduced to 0'6 mm., the results for the 

 original and final densities being as follows : 



Density of original wire = 8 '53 

 after being drawn = 8'615 



Effect of Twisting. 



A length of 130 cm. of 98 per cent, electrical conductivity wire, 

 diameter 2 mm., was fixed at one end to a support, and a weight of 



* Wire broke. 



