THE YOUNG 
the stone around, so as to give the glass a 
smooth convex surface. 
Now tie a piece of thin doeskin or other 
firm and thin woolen cloth, over the con- 
cave surface of the tin polisher, fastening 
it around the sides of the head. Slightly 
moisten the cloth, and put a small quan- 
tity of putty powder (oxide of tin) over it. 
Eemove the wooden centre, with the 
glass, from the mandrel, and insert the 
polisher. Set the polisher revolving, and, 
using the wooden centre as a handle, press 
the glass into the concavity, which it will 
fit accurately. Keep up the application 
of moisture and putty powder frequently. 
Do not let the glass get hot enough to 
melt the cement, but remove it frequently 
to cool. Do not hold the glass in one 
position, but keep the hand moving across 
the plane of the polisher in every direc- 
tion, taking care that in whatever i^osition 
the hand is held the glass fits accurately 
into the polisher. If the doeskin gets 
worn through, replace it with another 
piece. When the polishing has proceeded 
so far that the surface of the glass ap- 
pears brilliant, and no scratches remain 
visible to the naked eye, the dampening 
and application of putty powder should 
be stopped, and the polishing continued 
with what putty powder has worked into 
the cloth. The polishing will not take 
very much time if the grinding was pro- 
perly finished with fine stone, as directed. 
It should be continued, however, until 
under a magnifying power of ten diame- 
ters the surface of the glass appears as 
bright and free from scratches as it does 
to the naked eye. 
The lens can now be heated enough to 
melt the cement, when it can be slid from 
the wood, A little alcohol will remove 
the cement remaining upon it. If the 
whole process has been conducted ac- 
cording to directions, the lens should 
give a clear bright view of any object, 
as the words on this page, and, while 
looking, no sign of distortion should be 
visible on turning the glass around in the 
fingers. 
In shaping and polishing the lenses, as 
in everything else, practice makes per- 
fect. Care and attention to details are all 
that are needed, and after the process has 
SCIENTIST. 53 
become familiar it will be found easy, so 
that any one can make for himself a sup- 
ply of lenses of various powers, and even 
make combinations that will do excellent 
service. 
Middlebury, Vt., Jan. 11, 1879. 
► ♦ . 
The Graver. 
BY JOSHUA KOSE, M. E. 
WHAT a wonderful field of usefulness 
that simple looking little tool, the 
graver, fills! It is used upon wrought 
iron, steel, copper, cast iron, brass and 
w^ood, as well as upon ivory, bone, tin, 
leadj and the softer metals, and it will cut 
Fig. 1. 
in almost any position in which its cut- 
ting edge can be brought to bear upon the 
work. 
It consists of a square piece of steel, 
with the end face ground off at an angle, 
as shown in Fig. 1. The edges. A, A, ex- 
tending on each side from B to C, as well 
as the point, B, being used to cut with. 
The machinist uses its point to cut work 
very true, holding it in the position shown 
Fig. 2. 
in Fig. 2, while to finish the work smooth 
he holds it as shown in Fig. 3. The brass 
finisher bevels off the face, as shown in 
Fig. 4, and the engraver turns it upside 
down as shown in Fig. 5, using the point, 
B, only. It will cut work that is parallel. 
