Page:Popular Science Monthly Volume 91.djvu/479

 Popular Science Monthly

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��is simple, efficient, inexpensive and small. A small commercial house could, in some cases, use the plan to advantage. The outfit can be placed on the wall of the dark room in an unused corner. Made in

���This method of development economizes in chemicals, as a very small quantity is required

approximately the dimensions shown, which may be varied to suit the conditions, it will accommodate from 10 to ioo ft. of film and it will use less than I quart of developer per ioo ft. of film.

The film to be developed is wound around the rollers as if it were a belt, with the emulsion side out. The upper bracket carrying one of the multiple rollers is adjustable for different lengths of film, so that the single idler will serve to compensate for the slight variation in the film length during developing and drying. When ad- justed properly the ends of the film are spliced together, thus making a continuous belt. The upper set of rollers consists of a flanged stick on a shaft equipped with a grooved pulley so arranged that it can be belted to a motor or, in the absence of a motor, to another wheel placed con- veniently and fixed in a way to enable the operator to run the apparatus by hand.

The developing pan or tray is preferably an enameled baking pan which can be partially filled with either developer, water or hypo solution and raised underneath the bottom set of rollers so as to immerse the running film into the several liquids as desired. The film can be stopped and examined at any time and the solutions changed in a few moments, especially if the

��operator has a pan for each solution. After development, fixing and washing, the film may be quickly dried by running it over the rollers while the air from a fan is turned on it, provided the room is free from dust, which is essential for all the work.

In setting the apparatus for any length of film it can be marked on a scale for future use, or by the use of a tape line the device can be calibrated and marked so the rollers may be set at once and properly for any length of film. The entire apparatus should be painted with paraffin dissolved in gasoline to prevent the wood from wetting and swelling, and to prevent the absorption of fluids by the unprotected parts of the frame. — T. B. Lambert.

���A driver to turn studs in aluminum

��A Driver to Turn Studs in Aluminum Castings

METAL workers who attempt to put studs into aluminum castings usually do the job with tools not intended for the work. A very handy tool may be made for this work, as shown in the illustration. It will be necessary to have a set of these tools, one for each size stud used. The stud is screwed into the tool as far as it is necessary ; then the center piece is screwed down tight upon it to hold the stud in place. The stud may be driven tight into the casting and the center piece loosened ; then the tool may be turned off from the stud with perfect ease, leaving the stud set. The shank of the tool is made of hexagon stock and the center piece of ^8-in. round ma- chine steel. — Theron L. Winchip.

A Lasting Paint for Covering a Heated Surface

A GOOD black, heat-resisting paint for the front of a locomotive, or other place subject to heat, can be made in the following manner: Shave 6 pounds of brown soap and melt it in water, then add more water to make it up to 12 gal. Mix in 18 gal. of Japan oil, then stir in 80 lb. of the best graphite. This will make about 35 gal. of paint. Stir the mass well and apply while the object is not too hot.

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