[Illustration:  Sounder-A. brass:  B. wood:  C. soft iron; DD. coils wound with No. 26 wire:  E. nail soldered on A; FF. binding posts:  H spring]

The stop, K, is a wire nail driven deep enough in the base to leave about 1/8 in. between the armature and the magnet.  The binding posts, F, may be taken from old dry batteries and are connected to the two wires from the magnet by wires run in grooves cut in the base.

The base of the key, Fig. 2, is also made of wood and has two wooden bearings, E, which are made to receive a pivot, similar to the one used in the sounder.  The lever of the key is made of brass and has a hardwood knob, A, fastened near the end.  A switch, D, connects with the pivot at F and can be either made from sheet brass, or taken from a small one-point switch.  The binding posts are like those of the sounder, and are connected to the contacts, K, by wires run in grooves cut in the wood.

[Illustration:  Key-A. wood; B. brass or iron soldered to nail; C. brass; D. brass:  E. wood:  F. connection of D to nail; HH. binding posts]

** How to Make a Music Cabinet [77]

A neat music cabinet can be made as shown in the accompanying sketch.  Each side, AA, Fig. 1, is cut from a board about 36 in. in length and 16 in. wide.  Both are alike and can be cut from the same pattern.  As the front legs curve out a little the main body of the boards AA should be 15 in. wide.  The back, B, should be about 22 in. long by 16 in. wide and set in between sides AA.  Cut the top, C, 16 in. long and 14-1/2 in. wide.  The bottom must be the same length as the top and 13-1/2 in. wide.

The door, D, can be made panel as shown, or a single piece, 16 in. wide and about 20 in. long.  All material used is to be made from boards that will dress to 3/4 in. thick.

[Illustration:  How to Make a Music Cabinet]

Shelving may be put in as shown in Fig. 2 and made from 1/4-in. material.  Make 12 cleats, E, 13-1/2 in. long, from a strip of wood 1/2 by 3/4 in., with a groove 1/4 by 1/4 in. cut in them.  Fasten 6 cleats evenly spaced on the inside of each of the sides, AA, with 3/4-in. brads.  This will give seven spaces for music and as the shelves are removable two places can be made into one.

** Easily Made Wireless Coherer [77]

A good wireless coherer may be made with very little expense, the only materials necessary being a glass tube, two corks:  a magnetized needle and a quantity of iron and silver filings.  Push a piece of wire through one cork and place in the bottom of the tube, as shown in the sketch.

Pour in the filings and insert the top cork with the needle pushed through

[Illustration:  Detail of Coherer]

from above.  The point of the needle should barely touch the filings and by slightly agitating the tube the iron filings will separate from the silver and cling to the magnetized needle, as shown.