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 as if glued to the casing.  You may now hang your hat on the end of the pencil.

When you slide the pencil along the casing, do it without any apparent effort, and it will appear to your audience as though you had hypnotized it.  This is a very neat trick if performed right.  Figure 1 shows the pencil on the casing and Fig. 2 the hat hanging on it.

[Illustration:  Pencil Trick]

** Tying a Knot for Footballs [133]

One of the most prominent English football clubs kept the tying of this knot on the rubber hose of their football a secret and never allowed all of its members to know how it was tied.  This tie can be used on grain sacks, and in numerous other like instances.  Make one loop in the cord and then another exactly the same way, as

[Illustration:  A Secure Knot]

shown in Fig. 1, placing the end of the cord under the first loop, then pulling at each end of the cord as in Fig. 2.—­A.E.J.

** Stove polish [133]

Stove polish consists of 2 parts graphite, 4 parts copperas and 2 parts bone black, mixed with water to form a paste.

** How to Give an Electric Shock While Shaking Hands [133]

There is nothing quite so startling as to receive an electric shock unexpectedly and such a shock may be given to a friend while shaking hands upon meeting.  The shock produced is not harmful and the apparatus can be carried in the pocket.  It consists of a small induction coil that can be constructed at home.

The core of the coil, A, Fig. 1, is constructed in the usual manner, of small soft-iron wire to make a bundle about 3/16 in. in diameter and 2 in. long.  The coil ends are made from cardboard, about 1 in. in diameter, with a 3/16-in. hole in the center.  The hole

[Illustration:  Details of Induction Coil]