sketch. This frame should be about 10-1/2 in.
long with the upper or wider part 4 in. long, and the lower part
6-1/2 in. long. The width should be about 5-1/4 in. at

[Illustration: Arc Lamp]

the top and 4 in. at the bottom. A cross bar, L, made of the same
material, is fitted into the off-set in the frame and riveted.
Holes are drilled through the frame and brass bushings, H and J,
are fitted for bearings to receive the adjusting brass rod, B,
which should be 1/4 in. in diameter. A brass curtain rod can be
used for the rod B, and on its lower end a socket, P, is soldered.

A piece of brass 2 in. long, 1/2 in. wide and 1/8 in. thick is
used for the armature, A, to be operated by the magnet coil, C.
The coil, C, is made in the usual manner by wrapping No. 14
cotton-covered magnet wire on a wooden spool that has a soft iron
core. The spool is about 2-1/2 in. long. The armature, A, is
drilled, making a hole just a little larger than the rod, B, and
is adjusted in place by two set screws, D and E. A soft piece of
iron, F, is fastened to the opposite end of the armature with a
screw, which should be placed directly under the end of the coil's
core. This end of the armature may be kept from swinging around by
placing it between a U-shaped piece of brass fastened to the cross
piece L. At the bottom end of the frame, and directly centering
the holes H and J, a hole is drilled to receive a hard rubber
bushing, R, for insulating the brass ferrule, S, that holds the
lower carbon.

One connection is made from the main to the upper binding-post,
which is in turn connected to one terminal of the coil, C, the
other coil terminal being attached to the frame. The other main
connection is made to the lower binding-post, which is also
connected to the brass ferrule, S, by soldering. The two
binding-posts are insulated from the frame the same as the ferrule
S. When using on a 110-volt circuit there must be some resistance
in connection, which may be had by using German silver wire, or a
water rheostat heretofore described.
--Contributed by Arthur D. Bradlev. Randolph, Mass.

** Irrigation [132]

The Mexican government has appropriated $25,000,000 for irrigation
work.

** How to Hang Your Hat on a Lead Pencil [133]

Take a smooth hexagon lead pencil, one without either rubber or
metal end, and place it against a door or window casing; then with
a firm, heavy pressure slide the pencil some 3 or 4 in. and it
will stay a