The point for the swivel bearing was determined by balancing the bed plate, with all parts in place, across the thin edge of a board.  There a 1/4-in. hole was bored in which shaft G turned.  To lessen the friction here, washers were placed under pulley F. The swivel bearing was made from two lids of baking powder cans.  A section was cut out of one to permit its being enlarged enough to admit the other.  The smaller one, 0, Fig. 6, was nailed top down with the sharp edge to the underside of the bed plate, so that the 1/4-in. hole for the shaft G was in the center.  The other lid, G, was tacked, top down also, in the center of the board P, with brass headed furniture tacks, R, Fig. 6, which acted as a smooth surface for the other tin to revolve upon.  Holes for shaft G were cut through both lids.  Shaft G was but 1/4 in. in diameter, but to keep it from rubbing against the board P, a 1/2-in. hole was bored for it, through the latter.

The tower was made of four 1 by 1 in. strips, 25 ft. long.  They converged from points on the ground forming an 8-ft. square to the board P at the top of the tower.  This board was 12 in. square and the corners were notched to admit the strips as shown, Fig. 1.  Laths were nailed diagonally between the strips to strengthen the tower laterally.  Each strip was screwed to a stake in the ground so that by disconnecting two of them the other two could be used as hinges and the tower could be tipped over and lowered to the ground, as, for instance, when the windmill needed oiling.  Bearings for the shaft G were placed 5 ft. apart in the tower.  The power was put to various uses.

** How to Make a Telegraph Instrument and Buzzer [334]

The only expenditure necessary in constructing this telegraph instrument is the price of a dry cell, providing one has a few old materials on hand.  Procure a block of wood about 6 in. long and 3 in. wide and take the coils out of an old electric bell.  If you have no bell, one may be had at the dealers for a small sum.  Fasten these coils on the blocks at one end as in Fig. 1.  Cut a piece of tin 2 in. long and 1/2 in. wide and bend it so the end of the tin

[Illustration:  Home-Made Telegraph Instrurment]

when fastened to the block will come just above the core of the coil.  Cut another piece of tin 3 in. long and bend it as shown at A, Fig. 2.  Tack these two pieces of tin in front of the coils as shown in the illustration.  This completes the receiver or sounder.

To make the key, cut out another piece of tin (X, Fig. 1) 4 in. long and bend it as shown.  Before tacking it to the board, cut off the head of a nail and drive it in the board at a point where the loose end of the tin will cover it.  Then tack the key to the board and connect the wires of the battery as in Fig. 1.  Now, move the coils back and forth until the click sounds just the way you wish and you are ready to begin on the Morse code.

When tired of this instrument, connect the wire from the coils to the key to point A and the one connected at the point under the key to B, leaving the other wire as it is.  By adjusting the coils, the receiver will begin to vibrate rapidly, causing a buzzing sound.  —­Contributed by John R. McConnell.