Page:Popular Science Monthly Volume 89.djvu/616

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��Popular Science Monthly

��Drying Negatives by Heat from a Kerosene Lamp

THE invention illustrated is a simple lamp heater for (juickly drying photographic plates. In the old form of lamp heater, the hot air from the lamp is made to circulate in a chamber con-

���The hot air passing over the plates is not exposed to gases

��taining the [)lates, l)ut this exposes the plates to the gases formed by the com- bustion of the lamp and also to smoke, especially if, as often happens, the lamp does not burn well. In the new makeup, care is taken that the plates are exposed only to fresh air. As will be seen, the lamp is placed in the sheet-iron box, but it occui)ies a separate chamber. The lamp chimney projects up into a tube portion, and is prevented from over- heating the metal by the use of an asbestos packing. The photographic plates are placed in two inclined cham- bers which open into the lamp chamber. The action of the lamp causes a suction in the ui)per tul)e clue to the rising current (jf liot air, and this causes air to be tirawn into the front opening A. The air passes up through the two plate chambers and out through the ciiinmey. Only fresh air circulates in the iilate chambers. Plates are first put in metal frames and these are slid into racks inside the chamber through the end door. If desired, .i ruby glass Iront can be used at C so as to make the devi(X' useful as a dark-room 1. intern.

��Making a Scrap- Book Out of Old Ledger Covers

A SCRAP- BOOK can be made at home from an old ledger back, pa]5er, twine, and glue, as follows: Take an old ledger and remove from it all pages, saving only the back. Next take about one hundred sheets of heavy type- writer paper (the number depends on the thickness of the ledger) and cut these to a size a little smaller than the back of the ledger. Between each of the pages place a thin strip of cardboard abf)ut ^2 in. wide. Now take some sharp in- strument, such as a large darning needle, and punch holes through the edge of the sheets of paper that contain the thin strips of cardboard. Place these holes about 2 in. apart. After they have been made, thread the needle with twine and sew them looseh' together by passing the needle and thread in and out of the holes you ha\c punched.

When the sheets are fastened together take a piece of linen cloth as long as the sheets of paper and about 4 in. in width. Where they have been fastened together wet the edge with glue and press it in the center of the cloth. After it has dried put the sheets in the ledger cover and fasten it there by^ gluing the cloth that extends out on each side of the sheets to the inside of the ledger cover. When it is thoroughly dried you have a scrap book that has cost you little or nothing.

��A Thumb-Tack Gage for a Paper- Cutting Board

THIC drawing shows an accurate and easily apjilied method of gaging a cutting-board to trim exactly to size anv number of sheets. It consists of a

���The thumb-tnck can be set at any desired point on the cutting-board for a gage

tiuunii-tack stuck into the cutting-board surface at the riglit spot to hold the edge of the i)ai)er in i)lace. — C. P. I.KllMANN.

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