The Boy Mechanic Part 45

[Ill.u.s.tration: Old Pulleys and Pipe Fittings]

other, which connects all arms together on both sides of the wheel. Mounted on the shaft with the pulleys is a guide for the kite wire or string. The photograph shows that this guide permits of being moved entirely over the top of the reel. The smaller pulley is attached to the shaft and used as a brake. The brake is used only when running out the wire or string, first removing the crank.

** Attaching Runners to a Bicycle for Winter Use [157]

Instead of storing away your bicycle for the winter, attach runners and use it on the ice. The runners can be made from 1/4-in. by 1-in. iron and fastened to the bicycle frame as shown in the sketch. The tire is removed from the rim of the rear wheel and large screws turned into the rim, leaving the greater part of the screw extending. Cut off the heads of the screws and file them to a point. The rear runners should be set so the rim of the wheel will be about 1/2 in. above the runner level.

--Contributed by C. R. Welsh, Manhattan, Kan.

[Ill.u.s.tration: Bicycle Fitted with Runners for Snow]

** A Paper That Makes Green Prints [157]

A coating for ordinary paper that is said to give green prints is made with a two per cent solution of gelatine, says Photography, and sensitized with the following solution:

Pota.s.sium Bichromate 15 gr.

Magnesium Sulphate 25 gr.

Water 1 oz.

This mixture is spread over the paper in the usual way and the paper dried in the dark. Printing is carried rather far. The print is washed, then surface dried or blotted off on a pad and laid film upwards on a sheet of gla.s.s, and the following developer is applied with a wad of cotton wool wrung out:

Pyrocatechin 5 gr.

Water 1 oz.

The picture a.s.sumes a rich green color when developed, and is then washed for five or ten minutes and dried quickly by heat.

** Copies Made from Wax Molds by Electro-Deposition [157]

Fine copies of wax impressions can be made in the following manner: Procure an ordinary tumbler and fill it with a strong solution of sulphate of copper, which is made by dissolving two cents' worth of blue vitriol in 1/2 pt. of water. After this is done make a porous cell by rolling a piece of brown paper around a stick and fastening the edge with sealing wax; also, fix a bottom to the cell in the same way. Make a solution of one part of oil of vitriol and 5 parts of water and pour this mixture into the porous cell. Wind the end of a copper wire around the end of a piece of zinc and place the zinc in the porous cell. Attach the other end of the wire to the wax impression.

The wax impression is made by pouring melted beeswax on the article you wish to reproduce and removing after the wax gets cold. The wax mold then should be coated with black lead and polished. This is done with a camel's hair brush. A fine copy can be made on the wax impression after the battery has been running about 12 hr.

--Contributed by Edward M. Treasdale.

[Ill.u.s.tration: Electro-Deposition]

** How to Make Skating Shoes [158]

Remove the clamp part, as shown in Fig. 1, from an ordinary clamp skate. Drill holes in the top part of the skate

[Ill.u.s.tration: Skating Shoes]

for screws. Purchase a pair of high shoes with heavy soles and fasten the skates to the soles with screws, as shown in Fig. 2.

When completed the skating shoes will have the appearance shown on Fig. 3. These will make as good skating shoes as can be purchased, and very much cheaper.

--Contributed by Wallace C. Newton, Leominster, Ma.s.s.

** How to Make a Self-Setting Rabbit Trap [158]

Secure a good-sized box, say, 1 ft. high, 1-1/2 ft. wide, and 3 ft. long; and to the bottom, about 10 in. from one end, fasten a 2-in. square piece, A, Fig. 1, extending the width of the box.

Place a 10-in. board sloping from the end of the box to the cleat A. The swing door B, Fig. 1, is made as shown

[Ill.u.s.tration: Self-Setting Trap]

in Fig. 2, which represents the back side of the door. Sheet metal or tin is cut to the proper size and tacked around the edge of the hole. This prevents the animal from gnawing its way out, also provides a way to make the hole of different sizes for squirrels or other animals. The hole in the door should be about 2 in. wide and 4 in. high for rabbits. The door is made to swing freely on two large nails driven through the sides of the box. The hole in the door being only large enough to admit a small portion of the rabbit's head, the rabbit will push its way through to the bait, causing the door to swing back and up, and it will close by its own weight when the animal is inside. A small door is provided in the other end to remove the animals caught.

The advantage of this trap is that where one animal is caught others are liable to follow, and several rabbits will be trapped at a time. Then, too, the rabbits are not harmed in any way as they would be if caught in an ordinary trap.

--Contributed by H. F. Church, Alexandria, Va.

** How to Make an Atomizer [158]

Secure a good-sized test tube and fit it with a cork. Take two gla.s.s tubes, with about 1/8-in. hole, and bend them as shown in the sketch. This is done by heating them at the proper point over a gas flame until they are soft. Two holes are bored through the cork and the bent tubes inserted in them, as shown in the sketch, so that one of the tubes will extend nearly to the bottom

[Ill.u.s.tration: Atomizer]

of the test tube and the other just projecting through the cork.

The spray tube may be made with a fine hole by first securing a tube longer than necessary and heating it at the proper point and drawing the tube out into a fine thread. The thread is broken off at the proper place to make a small hole.

** Home-Made Kits for the Camera [159]

If you have a 5- by 7-in. camera and wish to use some 4- by 5-in.

plates, make a few simple kits to hold the smaller plates and fit the larger holders, says Camera Craft. Take two pieces of pasteboard, A and B, black surfaced if possible, and exactly 5 by 7 in. in size. The piece A will form the back of the kit and should have an opening cut in the center 4 by 5 in. in size. Paste a piece of strong black paper, C, over the under side of it to keep the plate from falling through. Cut an opening in the other piece, B, but cut it 1/4 in. shorter. This opening, being 1/8 in.

shorter at each end, will retain the plate in position and cut off only that small amount of plate surface when the plate is exposed in the

[Ill.u.s.tration: Camera Kit]

camera. Cut a piece of thin black cloth, D, 1 in. wide and 5 in.

long. Lay it down on a piece of newspaper and coat one side with gum or mucilage. Stand the two pieces of 5 by 7 in. black cards on end together so that they will be square and true and bind the other ends with the strip of cloth so as to form a hinge. The two cards form a thickness about equal to a thick gla.s.s plate, and go in the holder in the same way. Lay one of these kits down against the ground side of the focusing screen and draw a line around, inside of the opening. This will be a guide as to just what will be secured upon the smaller plate when the kits are used.

** How to Make a Miniature Stage [159]

A good smooth box, say 8 in. wide, 10 in. high and 12 in. long, will serve the purpose for the main part of this small theater.

Out two rectangular holes, Fig. 1, one in each end and exactly opposite each other. Place a screw eye about 1/2 in. from the edge on each side of these openings. Fit an axle in the screw eyes and fasten a spool to the middle of the axle. On one of the two spools attach another smaller spool, Fig. 2, to be used as a driving pulley. Cut out the front part of the box down to a level with the top of the spools. Connect the spools with a belt made from tape about 3/4 in. wide. On this belt fasten figures cut from heavy paper and made in the form of people, automobiles, trolley cars, horses and dogs. A painted scenery can be made in behind the movable tape. The front part of the box may be draped with curtains, making the appearance of the ordinary stage, as shown in Fig. 3. A small motor will run the spools and drive the tape on which the figures are attached.

--Contributed by William M. Crilly, Jr., Chicago.

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