The Boy Mechanic Part 40

** Home-Made Toaster [139]

Each outside frame of the toaster is made from one piece of wire 30 in. long. These are bent in a perfect square making each side 7-in. long. This will allow 1 in. on each end for tying by twisting the ends together. The first two wires inside and on each side of each frame are 8 in. long. Eight wires will be required for this purpose and as they are 8 in. long 1/2 in. is allowed on each end for a bend around the outside frame, as shown in the sketch. The two middle wires are extensions of the handles. Each of these wires are made from a piece about 26 in. long and bent in the shape of a U. The ends of the wire are bent around the frame in the same manner

[Ill.u.s.tration: Toaster]

as the other wires. This will leave the handle laying across the other side of the frame. The frame is fastened to the handle on this side by giving the handle one turn around the frame. The inside edges of the frame are now tied together with a small ring of wire which is loose enough to allow each half to swing freely.

--C. D. M.

** Home-Made Shocking Machine [139]

An ordinary electric bell may be connected up in such a way as to produce the same results as an expensive

[Ill.u.s.tration: Inexpensive and Effectual]

shocking machine. The connections are made from the batteries to the bell in the usual manner. Two other wires are then connected, one to the binding-post of the bell that is not insulated from the frame and the other to the adjusting screw on the make and break contact of the bell as shown in the sketch. The other ends of the wires are connected each to a common table knife. This will give quite a good shock and a much larger one can be had by placing one knife in a basin of water and while holding the other knife in one hand, dipping the fingers of the other hand in the water.

--Contributed by D. Foster Hall.

** Mahogany Wood Putty [139]

Mix venetian red with quite thick arabic muscilage, making it into a putty, and press this well into the cracks of mahogany before finis.h.i.+ng. The putty should be colored to suit the finish of the wood, says the Master Painter, by adding such dry color to the gum as will give the best result.

** How to Make a Thermoelectric Battery [140]

By Arthur E. Joerin

A novel way of producing an electric current by means of hot and cold water, heat from a match or alcohol

[Ill.u.s.tration: Details of Battery]

lamp, is obtained from a device constructed as shown in the sketch. Take two hardwood boards, marble, or slate plates, about 8 or 10 in. long, place them together, as in Fig. 1, and mark and drill about 500 holes. These two pieces should be separated about 8 in. and fastened with boards across the ends, as shown in Fig.

2.

Take soft copper wire, not smaller than No. 18 gauge, and cut in lengths to pa.s.s through the holes in the two boards, leaving sufficient end to make a tie. It will require about 70 ft. of wire to fill one-half the number of holes. Also, cut the same number of lengths from the same gauge galvanized-iron wire to fill the remaining holes. The wires are put through the holes in the boards alternately, that is: begin with copper, the next hole with iron, the next copper, the next iron, and so on, twisting the ends together as shown in Fig. 3. The connections, when complete, should be copper for the first and iron for the last wire.

When the whole apparatus is thus strung, the connections, which must be twisted, can be soldered. Connect one copper wire to the bell and the other terminal, which must be an iron wire, to the other post of the bell. The apparatus is then short-circuited, yet there is no current in the instrument until a lighted match, or, better still, the flame of an alcohol lamp is placed at one end only.

Best results are obtained by putting ice or cold water on one side and a flame on the other. The experimenter may also place the whole apparatus under sink faucets with the hot water turned on at one terminal and the cold water at the other. The greater the difference of temperature in the two terminals, the more current will be obtained.

Very interesting experiments may thus be performed, and these may lead to the solving of the great thermoelectric problem.

** How to Make a Hygrometer [140]

Mount a wire on a board which is used for a base and should be 3/8 by 4 by 8 in., as shown in the sketch. A piece of catgut--a string used on a violin will do--is suspended from the bent end of the wire. A hand or pointer is cut from a piece of tin and secured to the catgut string about 1/2 in. from the base. A small piece of wood and some glue will fasten the pointer to the string. The scale is

[Ill.u.s.tration: Simple Hygrometer]

marked on a piece of cardboard, which is fastened to the base and protected with a piece of gla.s.s.

--Contributed by J. Thos. Rhamstine.

** Softening Leather in Gloves and Boots [140]

The leather in high-top boots and gauntlet gloves may be softened and made waterproof by the use of plain mutton tallow. Apply hot and rub in well with the fingers.

** How to Make a Mission Library Table [141]

The mission library table, the drawings for which are here given, has been found well proportioned and of pleasing appearance. It can be made of any of the several furniture woods in common use, such as selected, quarter-sawed white oak which will be found exceptionally pleasing in the effect produced.

If a planing mill is at hand the stock can be ordered in such a way as to avoid the hard work of planing and sandpapering. Of course if mill-planed stock cannot be had, the following dimensions must be enlarged slightly to allow for "squaring up the rough."

For the top, order 1 piece 1-1/8 in. thick, 34 in. wide and 46 in.

long. Have it S-4-S (surface on four sides) and "squared" to length. Also, specify that it be sandpapered on the top surface, the edges and ends.

For the shelf, order 1 piece 7/8 in. thick, 22 in. wide and 42 in.

long, with the four sides surfaced, squared and sandpapered the same as for the top.

For the side rails, order 2 pieces 7/8 in. thick, 6 in. wide and 37 in. long, S-4-S and sanded on one side. For the end rails, 2 pieces 7/8 in. thick, 6 in. wide and 25 in. long. Other specifications as for the side rails.

For the stretchers, into which the shelf tenons enter, 2 pieces 1-1/8 in. thick,

[Ill.u.s.tration: This Picture Is from a Photograph of the Mission Table Described]

3-3/4 in. wide and 25 in. long, surfaced and sanded on four sides.

For the slats, 10 pieces 5/88 in. thick, 1-1/2 in. wide and 17 in.

long, surfaced and sanded on four sides. For the keys, 4 pieces 3/4 in. thick, 1-1/4 in. wide and 2-7/8 in. long, S-4-S. This width is a little wide; it will allow the key to be shaped as desired.

The drawings obviate any necessity for going into detail in the

[Ill.u.s.tration: Table Details]

description. Fig. 1 gives an a.s.sembly drawing showing the relation of the parts. Fig. 2 gives the detail of an end. The tenons for the side rails are laid off and the mortises placed in the post as are those on the end. Care must, be taken, however, not to cut any mortises on the post, below, as was done in cutting the stretcher mortises on the ends of the table. A good plan is to set the posts upright in the positions they are to occupy relative to one another and mark with pencil the approximate positions of the mortises. The legs can then be laid flat and the mortises accurately marked out with a fair degree of a.s.surance that they will not be cut where they are not wanted and that the legs shall "pair" properly when effort is made to a.s.semble the parts of the table.

The table ends should be glued up first and the glue allowed to harden, after which the tenons of the shelf may be inserted and the side rails placed.

There is a reason for the shape, size and location of each tenon or mortise. For ill.u.s.tration, the shape of the tenon on the top rails permits the surface of the rail to extend almost flush with the surface of the post at the same time permitting the mortise in the post to be kept away from that surface. Again, the shape of the ends of the slats is such that, though they may vary slightly in length, the fitting of the joints will not be affected. Care must be taken in cutting the mortises to keep their sides clean and sharp and to size.