1880. | Microscopy. GF, * 
is represented in front view and in section in Figs. 3 and 4. It 
can be readily made by amateurs for their own use. It consists 
of a wooden body of such size as to be easily held and twirled 
between the fingers, with a short needle point inserted in the 
center of the lower end. On one side a longitudinal slot or 
groove is cut through the wood deep enough to allow the cut- 
ting edge to approach nearly to the needle. The cutter is of 
steel, one-eighth or three-sixteenths inch wide, as a piece of skirt- 
steel or corset-spring, and is attached so as to lie in the groove 
and press toward the needle. The cutter should be ground toa 
triangular point,-and ground only on the outside, leaving its 
inner face flat and smooth. A screw passes through the body of 
the instrument and bears against the spring, regulating its dis- 
tance from the needle point. -Greater firmness might be secured 
by changing the form of the body so as to support at its two 
edges the cutter when forced out to its farthest limit. The other 
instrument, shown in Fig. 5, was suggested by the Vorce instru- 
ment, and was contrived by Mr. Frank Ritchie, of Troy. It 
possesses greater power and precision than the other, but is not 
so easily made by an amateur. It consists of 
a pair of spring dividers about three and one- 
quarter inches long, from one leg of which — 
half an inch of its length has been cut off and 
replaced by a brass socket with a binding 
screw to hold a small knife blade. A knob is 
also added at the top for convenience in man- 
ipulation. The method of working these two 
forms of apparatus is precisely the same. A 
sheet of wax may be laid on a sheet of heavy 
white paper, and both together tacked to a 
piece of smooth hard wood. The instrument 
with its legs set three-sixteenths inch apart, 
iS used to cut outa series of discs of three- 
eighths inch diameter. How near together 
these can be safely cut will soon be learned 
by experience. The legs are then set one- 
quarter inch apart, and using the same centers 
as before, a series of rings can be cut suitable 
for one-half inch covers. B successively 
Spreading the legs one-sixteenth inch further 
each time, rings may be cut around the same 
_ Centers for five-eighths and three-quarters inch E eee 
Seo ee if desired. The concentric ee ~ Riedie T 
each center are cut out without curte. 
waste, as shown in Fig. 2. Not only wax but oes 
also sheet-lead, card-board and gutta percha can be cut with 
$e a ae ae ee 
_ facility in this manner. The various tools sold by hardware 
emp 
; Psi cutting washers of leather, etc., have often been e 
