** Burning Inscriptions on Trees

Scrape off the bark just enough to come to the first light under
coating, which is somewhat moist. With a lead pencil make an
outline of the inscription to be burnt on the tree and bring, the
rays of a large magnifying glass not quite to a fine focus on the
same. The tree will be burnt along the pencil marks, and if the
glass is not held in one spot too long, the inscription will be
burnt in as evenly as if it had been written.
--Contributed by Stewart H. Leland, Lexington, Ill.



** How to Make Small Gearwheels Without a Lathe [46]

To make small models sundry small gears and racks are required,
either cut for the place or by using the parts from an old clock.
With no other tools than a hacksaw, some files, a compass,

[Illustration: Making Model Wheels]

and with the exercise of a little patience and moderate skill,
very good teeth may be cut on blank wheels.

First take the case of a small gearwheel, say 1 in. outside
diameter and 1/16 in. thick, with twenty-four teeth. Draw a circle
on paper, the same diameter as the wheel. Divide the circumference
into the number of parts desired, by drawing diameters, Fig. 1.
The distance AB will be approximately the pitch. Now describe a