THE YOUNG SCIENTIST. 
141 
As some of my young readers may in 
their summer rambles come across the 
eggs of the Cecropia in a state of nature, 
I herewith give a figure of a leaf with the 
eggs as usually attached. Such leaves, if 
kept in the house, will soon hatch out, 
and the young caterpillars may be fed 
and reared in the way i- ready described. 
Something About Saws.— lY. 
BY "our NED." 
x4.VING fairly described, from 
an amateur's standpoint, the 
methods of filing and using 
hand-saws, I will now take up 
the smaller saws that the amateur will be 
sometimes called upon to use. 
The most common saw in use after the 
hand-saws and back-saw is the compass- 
saw, an illustration of which I give at 
Fig, 1, 
Fig, 
The average length of the blade of this 
kind of a saw is about twelve inches, but 
many of them are made longer, and some 
few of them shorter ; and the width of the 
blade is usually about one and a quarter 
inches near the handle, and one quarter 
of an inch at the point. They very much 
resemble the ordinary hand-saw in their 
general construction, the handle being 
attached to the blade by rivets, in the 
same manner as hand-saws, but being of 
a somewhat different shape. The teeth 
are formed very much like the teeth of a 
fine hand-saw designed for cross-cutting 
soft wood, being, perhaps, thrown a little 
further forward or made more hooking. 
In using these saws much care should 
be taken when following a line around 
curves having short radii, or it will be 
apt to "kink" or buckle, or perhaps 
break. To prevent this class of saws 
from snapping, I have often filed them, 
so that the teeth would pitch towards the 
handle instead of to the point; this ex- 
pedient forced the blade to perform its 
work on the pull stroke, which, in my 
opinion, is the proper manner for all 
narrow- b laded saws to labor, unless they 
are strained from both ends, like the 
bow-saw shown at Fig. 2, which, being 
held at both 
ends, will per- 
form its work 
nearly as well 
one way as an- 
other. 
Saw blades 
of this class 
should be thin 
on the back, which not only gives them 
clearance, but aids them materially to 
follow a line closely round short curves. 
The pad, socket, or key- hole saw is 
something shorter and narrower than the 
compass saw, and is not fas- 
tened to the handle perman- 
ently. The blades are sold 
separately, and may be ob- 
tained any length from six to 
fourteen inches, and containing 
teeth from eight to eighteen 
to the inch. Fig. 3 shows the 
wooden "pad" or handle gen- 
erally used for these kind of saws; 
there is a slit or mortice down the 
whole length of the handle, so that the 
blades can slip down, leaving only so 
much out of the handle as may be 
Figo do 
required. The blade is held in position 
by two set-screws, which are operated 
upon by a screw-driver. This is an excel- 
lent arrangement, as it enables the per- 
son using the saw to adjust its length to 
suit the work in hand. Saws that have 
been broken, if not too short, may be 
used again, but if it is the shank end of 
the saw that is used, the end should be 
