The Boy Mechanic Part 119

** How to Make an Ironing-Board Stand [429]

Secure some 1 by 3-in. boards, about 3 ft. long, and plane them smooth. Cut the two pieces A and B 30 in. long and make a notch in each of them, about one-third of the way from one end, 1 in. deep and 3 in. long. These

[Ill.u.s.tration: Ironing-Board Stand]

notches are to receive the piece D, which has a small block fastened to its side to receive the end of the brace C. The brace C is 36 in. long. The upper ends of the pieces A, B and C are fastened to a common ironing board by using iron hinges as shown in Fig. 1. As the piece D is fitted loosely, it may be removed and the brace, C, with the legs, A and B, folded up against the board.

--Contributed by Bert Kottinger, San Jose, Cal.

** A Home-Made Electric Plug [430]

[Ill.u.s.tration: Plug]

A plug suitable for electric light extension or to be used in experimenting may be made from an old electric globe. The gla.s.s is removed with all the old composition in the bra.s.s receptacle, leaving only the wires. On the ends of the wires, attach two small binding posts. Fill the bra.s.s with plaster of paris, and in doing this keep the wires separate and the binding-posts opposite each other. Allow the plaster to project about 3/4 in. above the bra.s.s, to hold the binding-posts as shown.

--Contributed by Albert E. Welch, New York.

** How to Make an Electric Fire Alarm [430]

On each end of a block of wood, 1 in. square and 1 in. long, fasten a strip of bra.s.s 1/4 by 3 in., bent in the shape as shown in the sketch at A, Fig; 1. These strips should have sufficient bend to allow the points to press tightly together. A piece of beeswax, W, is inserted between the points

[Ill.u.s.tration: Fire Alarm Device]

of the bra.s.s strips to keep them apart and to form the insulation.

A binding post, B, is attached to each bra.s.s strip on the ends of the block of wood. The device is fastened to the wall or ceiling, and wire connections made to the batteries and bells as shown in the diagram, Fig. 2. When the room becomes a little overheated the wax will melt and cause the bra.s.s strips to spring together, which will form the circuit and make the bell ring. Each room in the house may be connected with one of these devices, and all on one circuit with one bell.

** Home-Made Boy's Car [430]

[Ill.u.s.tration: Boys' Home-Made Auto]

The accompanying cut shows how a boy may construct his own auto car. The car consists of parts used from a boy's wagon and some old bicycle parts. The propelling device is made by using the hanger, with all its parts, from a bicycle. A part of the bicycle frame is left attached to the hanger and is fastened to the main board of the car by blocks of wood as shown. The chain of a bicycle is used to connect the crank hanger sprocket to a small sprocket fastened in the middle of the rear axle of the car. The front axle is fastened to a square block of wood, which is pivoted to the main board. Ropes are attached to the front axle and to the back part of the main board to be used with the feet in steering the car. To propel the auto, turn the cranks by taking hold of the bicycle pedals. --Contributed' by Anders Neilsen, Oakland, Cal.

** Photographs in Relief Easily Made [431]

Relief photographs, although apparently difficult to produce, can be made by any amateur photographer. The negative is made in the usual way and,

[Ill.u.s.tration: Reproduced from a Relief Photograph]

when ready for printing, a positive or transparency is made from it in the same manner as a lantern slide or window transparency, says the Sketch, London. Use the same size plate as the negative for the transparency. To make the print in relief place the positive in the frame first with the film side out and the negative on top of this with the film side up in the usual manner.

Put in the paper and print. This will require a greater length of time than with the ordinary negative on account of printing through double gla.s.s and films. In using printing-out papers care should be taken to place the printing frame in the same position and angle after each examination.

** Wireless Tip [431]

Place the transmitting instruments of a wireless outfit as close together as possible.

** How to Make a Wireless Telephone [432]

A noted French scientist, Bourbouze, was able to keep up communication with the outside during the

[Ill.u.s.tration: Details of Wireless Phone Installation]

siege of Paris by making practical application of the earth currents. The distance covered is said to have been about 30 miles. Another scientist was able to telephone through the earth without the aid of wires. Nothing, however, has been made public as to how this was accomplished.

It is my object to unveil the mystery and to render this field accessible to others, at least to a certain degree, for I have by no means completed my researches in this particular work.

In order to establish a wireless communication between two points we need first of all a hole or well in the ground at each point.

In my experiments I was unable to get a deep well, but the instruments worked fine for a distance of 200 ft., using wells about 25 ft. deep. As in ordinary telephone lines, we require a transmitter and receiver at each point. These must be of the long-distance type. If a hole is dug or a well is found suitable for the purpose, a copper wire is hung in the opening, allowing the end to touch the bottom. To make the proper contact an oval or round--but not pointed--copper plate is attached to the end of the wire. If a well is used, it is necessary to have a waterproof cable for the part running through the water. The top end is attached to the telephone transmitter and receiver, as in the ordinary telephone, to the batteries and to a zinc plate, which is to be buried in the earth a few feet away from the well or hole, and not more than 1 ft. under the surface. A battery of four dry cells is used at each station.

Both stations are connected in the same way, as shown in the sketch. This makes it possible for neighbors to use their wells as a means of communication with each other.

--Contributed by A. E. Joerin.

** Eyelets for Belts [432]

If eyelets, such as used in shoes, are put into the lace holes of a belt, the belt will last much longer. The eyelets, which may be taken from old shoes, will prevent the lace from tearing out. I have used this method on several kinds of belts, always with entire satisfaction.

--Contributed by Irl R. Hicks.

** How to Make a Life Buoy [432]

Any boy may be able to make, for himself or friends, a life buoy for emergency use in a rowboat or for learning to swim. Purchase 1-3/4 yd. of 30-in. canvas and cut two circular pieces, 30 in. in diameter, also cutting a round hole in the center of them, 14 in.

in diameter. These two pieces are sewed together on the outer and inner edges, leaving a s.p.a.ce, about 12 in. in length, open on the outer seam. Secure some of the cork used in packing Malaga grapes from a grocery or confectionery store and pack it into the pocket formed between the seams through the hole left in the outer edge.

When packed full and tight sew up the remaining s.p.a.ce in the seam.

Paint the outside surface and the seams well with white paint to make it water-tight.

--Contributed by Will Hare, Petrolea, Onto

[Ill.u.s.tration: Buoy]

** A Home-Made Microscope [433]

A great many times we would like to examine a seed, an insect or the fiber of a piece of wood but have no magnifier handy. A very good microscope may be made out of the bulb of a broken thermometer. Empty out the mercury, which is easily done by holding the bulb with the stem down over a lamp or candle. A spirit lamp is the best, as it makes no smoke and gives a steady heat. Warm the bulb slowly and the mercury will be expelled and may be caught in a tea cup. Do not heat too fast, or the pressure of the mercury vapor may burst the gla.s.s bulb, cautions the Woodworkers' Review. To fill the bulb with water warm it and immerse the end of the tube in the water. Then allow it to cool and the pressure of the air will force the water into the bulb.

Then boil the water gently, holding the bulb with the stem up; this will drive out all the air, and by turning the stem or tube down and placing the end in water the bulb will be completely filled. It is surprising how much can be seen by means of such a simple apparatus.