** How to Cross a Stream on a Log [94]

When crossing a water course on a fence rail or small log, do not face up or down the stream and walk sideways, for a wetting is the inevitable result.  Instead, fix the eye on the opposite shore and walk steadily forward.  Then if a mishap comes, you will fall with one leg and arm encircling the bridge. —­C.  C. S.

** Relay Made from Electric Bell [94]

It is not necessary to remove the adjusting-screw when changing an electric bell into a relay.  Simply twist it around as at A and bend the circuit-breaking contact back as shown.  It may be necessary to remove the head of the screw, A, to prevent short-circuiting with the armature.  —­Contributed by A. L. Macey, New York City.

[Illustration:  Relay]

** Foundry Work at Home [95]

** I The Equipment [95]

Many amateur mechanics who require small metal castings in their work would like to make their own castings.  This can easily be done at home without going to any great expense, and the variety and usefulness of the articles produced will make the equipment a good investment.

With the easily made devices about to be described, the young mechanic can make his own telegraph keys and sounders, battery zincs, binding posts, engines, cannons, bearings, small machinery parts, models and miniature objects, ornaments of various kinds, and duplicates of all these, and many other interesting and useful articles.

The first thing to make is a molding bench, as shown in Fig. 1.  It is possible to make molds without a bench, but it is a mistake to try to do this, as the sand is sure to get on the floor, whence it is soon tracked into the house.  The bench will also make the operation of molding much easier and will prove to be a great convenience.

The bench should be made of lumber about 1 in. thick and should be constructed in the form of a trough, as shown.  Two cleats, AA, should be nailed to the front and back to support the cross-boards, be, which in turn support the mold while it is being made.  The object of using the cleats and removable cross-boards instead of a stationary shelf is to give access to the sand, C, when it is being prepared.

About one or two cubic feet of fine molding-sand will be required, which may, be purchased at the nearest foundry for a small sum.  Yellow sand will be found a little better for the amateur’s work than the black sand generally used in most foundries, but if no yellow sand can be obtained the black kind will do.  If there is no foundry

[Illustration:  Fig. 1 — Convenient Arrangement of Bench and Tools]

near at hand, try using sand from other sources, giving preference to the finest sand and that which clings together in a cake when compressed between the hands.  Common lake or river sand is not suitable for the purpose, as it is too coarse and will not make a good mold.