138 Miscellaneous Intelligence. 
obtain the desired effect, by which means the apparent surface was in- 
creased rather than diminished, and the flaws and yellow tinge were 
removed 
ved. 
“* The process of diamond-cutting is effected by an horizontal iron 
plate of about 10 inches diameter, called a Schyf, or mill, which re- 
volves from two thousand to three thousand times per minute he 
diamond is fixed in a ball of pewter at the end of an arm, resting upon 
the table in which the plate revolves ; the other end, at which the ball 
containing the diamond is fixed, is pressed upon the wheel by moveable 
weights at the aan of the workman. The weights applied vary 
from 2 to 30 Ibs. acco 
aw 
at C, described by Professor Tennant and the Rev. W. Mitchell as 
amined it,) to be a natural flaw of a yellow tinge, a defect often met 
portant by the cutters was removing a flaw at G. This flaw was not 
thought by Professor Tennant and Mr. Mitchell to be dangerous, be- 
cause, if it were allowed to run according to the cleavage, it would only 
take off a small piece, which it was necessary to remove in order to — 
acquire the present shape. The cutters, however, had an idea that 
might not take the desired direction, and, therefore, began to cut into : 
ceeded in getting rid of it. While cutting, the stone appeared to 
become harder and harder the farther it was cut into, especially just 
the mill at the medium rate of 2400 times per minute, for six hours, 
little impression had been made; the speed was, therefore, increased to 
an 3000, at which rate the work gradually proceeded. When 
See eee 
