68 
ACCESSORY APPARATUS. 
paratus. Through this cylinder passes a steel stem, ending be- 
low ill a conical base of brass, in the bottom of which is insert- 
ed a piece of cork or india rubber to press upon the thin 
glass and hold it steady. At the top is a milled head «, under 
which is a helical spring, which supports the stem, and lifts it 
from the glass when not in use. Outside the cylindrical guide 
is a tube o, carrying a milled head and the socket n, to 
which is attached the bent arm c, carrying the waiting dia- 
mond d. The diamond is secured by a screw, and the arm 
which carries it can be extended at pleasure, and secured by 
the screw attached to the socket. The brass cone at the base 
of the stem supports the tube c>, but the tube can be raised on 
the cylindrical guide, so that the diamond presses upon the 
glass only by the weight of the arm <?, and tube o. 
To use this instrument, set the diamond at such a distance 
from the axis as is required to make the circular covers of thin 
glass of suitable diameter, lay the thin glass to be cut upon a 
plate of glass previously moistened so as to make the thin glass 
adhere ; slide the plate carrying the thin glass under the dia- 
mond, and hold it firmly by placing a finger upon the milled 
head a ; the diamond will then rest gently upon the glass, and 
may be revolved by turning the milled head h. Kemoving 
the pressure from move the plate and thin glass to a position 
convenient for cutting another circle, and so continue till the 
piece of thin glass has been all cut into circles. When the 
plate is removed the circles of thin glass can be easily separa- 
ted. The thin glass lies more firmly in its place, and is less 
liable to crack when laid upon a plate of wet glass, than if laid 
upon wood or dry glass. In turning the milled head 5, care 
should be taken not to press too heavily upon the diamond 
point. A very light cut only is required, while a heavy scratch 
is apt to fracture the glass. 
Glass covers may be cut of different sizes, so as to use up all 
irregular fragments of thin glass, which could not be profitably 
cut into squares. 
Circular covers in general look better upon microscopic ob- 
jects than squares, and with this instrument they may be cut 
J. k W. GRUNOW & GO’S ILLUSTRATED 
