28 H. Goadby on making wet Preparations of Animal Sui ta 
Babbage, the inventor of the celebrated calculating machine. 
Mount a glazier’s diamond to cut a circle; this can be done ina 
variety of ways—I have mounted my diamond as shown in 
fig. 6. a@represents a square bar 
of iron, 8 inches long, with a 
male screw at the lower end to fit 
a plate of iron (7) tapped to re- 
ceive it, b, b, twoarms 4$ inches 
long, clamped to the upright bar 
by thumb screws, the other ex-. 
tremity drilled and ground to re- 
ceive c, which isa spindle, to the 
lower end of which is rivetted a 
screwed rod d, 4 inches long from 
the center. e isa box to receive 
the glazier’s diamond when re- 
moved from the handle, and kept 
in its place by a tightening screw; 
continuous with this box is a fp mz 
square nut, f, perforated with a . 
hole large enough to allow it to swing freely on the screwed 
arm. 2,2, are square screwed nuts, one on each side of the dia- 
mond box. ; 5 
In adjusting the diamond to cut a disc, say three inches diam- 
eter, move it along the screwed arm until the point be coincident — 
with 13 inch as marked upon the scale (2) which has before been 
drawn upon the chamois leather which covers the board K ; then 
bring the nuts close to either side of the diamond box, adjust it 
to its cutting angle, and then by means of a wrench in each 
hand dighten the nuts simultaneously. The glass to be cut may 
now be placed upon the board ; remove the pin h, and lower the 
spindle (¢) till the diamond touch the glass: then holding the; 
screwed arm by one hand, turn it steadily round and it will de- 
scribe a circle of the size to which the diamond has been pre- 
viously adjusted. 
As the spindle has been ground to fit the two collars through 
which it works, the motion is smooth and steady. Such a ma- 
chine would be improved by casting the upright bar and the two 
arms in one piece: the height need not exceed six inches. Hav- 
ing cut a circle on a piece of glass, if the dise be wanted, cut 
the glass in three or four places from the circular cut to the outer 
edge, and carefully break off the pieces; but if a cel be wanted 
the dise must be removed without injury to the remainder of the 
glass, which is to form the walls of the required cell. as 
The cut, already made, gives the exact dimensions of the 
aperture required ; now alter the position of the diamond on the © 
screwed arm and cut a circle within the first, adjust again and | 
ct ee caerp ayew Ts meee ae 
