Adams <& Coker — The Floio of Marble. 471 



Fig. 2. 



HARD 

 CARBON 

 STEEL 



NICKEL 

 STEEL 



about 4 cm (1*56 inch) long. In the earlier experiments the 

 rock was first ground into rough columns 6 cm long and 2*5 cm 

 in diameter on a rubbing bed. Subsequently a small diamond 

 drill was installed having a hollow bit, which proved an excel- 

 lent device for readily securing a rough column of any rock 

 which it was desired to use for experimental work. This was 

 then cut into lengths and 

 turned into columns of the 

 required size in a lathe. The 

 final very accurate shaping 

 of the columns was given to 

 them by grinding with an 

 emery or corundum wheel 

 while in the lathe. In this 

 way the little columns were 

 turned to the desired shape 

 with extreme accuracy. 

 They were not as a general 

 rule made exactly cylindri- 

 cal in shape, but in order to 

 secure a very accurate fit 

 were usually made slightly 

 conical with a taper of 

 1/1000 of an inch in their 

 length. 



In the same way the steel 

 tube was first turned in a 

 lathe in the usual manner, 

 the inner surface was then 

 ground to secure greater 

 accuracy of shape, and the 

 tube was finally finished by 

 the employment of a reamer. 

 In this way a taper identi- 

 cal with that given to the 

 column was secured, the 

 column, however, being 

 slightly larger than that por- 

 tion of the tube which was 

 to enclose it. The tube was 

 then heated by placing a red 



hot iron ring about it and when thus expanded the rock was 

 gently shoved into it to the required position, and the tube 

 being allowed to cool, a mechanically perfect fit of the tube to 

 the column was secured. 



When it is desired to carry out the deformation at tempera- 

 tures above that of the laboratory and up to 600° C. or more, 



HARD NOVO 

 STEEL 



