the pulley and fastened to the shaft as shown in Fig. 7.

The bearings are made of oak blocks lined with heavy tin or sheet
iron for the running surface. Motion is transmitted from the
engine to the large pulley by a thin but very good leather belt.



** Homemade Telegraph Key [21]

A simple and easily constructed telegraph key may be made in the
following manner: Procure a piece of sheet brass, about 1/32 in.
thick, and cut out a strip 3-1/2 in. long by 3/4 in. wide. Bend as
shown in Fig. 1 and drill a hole for the knob in one end and a
hole for a screw in the other. Procure a small wood knob and
fasten it in place with a small screw. Cut a strip of the same
brass 2-3/4 in. long and 5/16 in. wide and bend as shown in Fig.
2. Drill two holes in the feet for screws to fasten it to the
base, and one hole in the top part for a machine screw, and solder
a small nut on the under side of the metal over the hole.

Mount both pieces on a base 4-1/4 by 2-3/4 by 1/4 in., as in Fig.
3, and where

[Illustration: Brass Key on a Wood Base]

the screw of the knob strikes the base when pressed down, put in a
screw or brass-headed tack for a contact. Fasten the parts down
with small brass wood-screws and solder the connections beneath
the base. Binding posts from an old battery cell are used on the