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Page:Popular Science Monthly Volume 89.djvu/946

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��Popular Science Munlhly

��BC and BD equal to EA. Stick in a pin at E and D. Tic a string around the two pins in a loop which, when pulled tight by inserting a pencil point as shown, will lie on the triangle BCD. If the pencil point is now moved carefully around the two pins, keeping the string stretched taut, it will describe the required ellipse.

Thin mats, masks for passe-partout, etc., can also be cut by this method. Always press between damp blotters, and afterward between dry ones to remove the creases. It cannot be used, however, on material thick enough to crush or break when folded, without marring the work. In this case the work should be laid out on the back of the mat with a pencil and cut carefully to outline with a sharp knife. A penknife is not a suitable tool for thick mats. The best tool for the work is a common one-piece steel table knife, broken within i32 in- of the handle and ground to a dagger point.

��where there is a low ceiling, as the hooks may be attached directly to the floor and ceiling. — A. B. Wegener.

��TO char trailir



��A Buffer to Stop Sprinters in Indoor Sports

TO take the place of large gymnasium mats, or a wood track with an eleva- tion at the end to retard the speed of sprinters in indoor sports the arrangement shown in the il- lustration has been devised. It consists of a framework to set against the wall with a base and top extension for attaching a can- vas buffer. The f r a m e w o r k should be of a size to hold a canvas 6 ft. long by 3 ft. wide, with suitable ropes hemmed in at the sides of the canvas and their ends extending for fastenings. The lower ends of the ropes are provided witii hooks which catch into rings on the base or into plates fastened to the lloor. The upper ends have a coil-spring and a hook on each one to make attaclinient to the top of the frame or ceiling.

Athletes running strike the canvas witii a turn so that it th^-ows them back ligiiiK' on the ir.M k. The frame is not necessary

��Removing Collar on Change-Gear Spindle of Lathe

lange over gears for compound ing on a lathe to cut threads it necessary to remove the belt-cone and reverse the gear A and collar B. The collar is difficult to remove because of its smoothness and its close fit to the boss face on the lathe head. This may be easily ac- complished if a small groove is filed in the collar at C suffi- ciently deep to take the enil of an ordi-




�- I



� �/B 1


Groove for easily re- moving collar when using compound gears

nary screwdriver.

���A frame built up to hold a canvas for stopping indoor runners

��Making Extended Index Tabs for Books

TAKE a piece of heavy, gummed paper tape 2 in. wide by alsout 14 in. long and fold it in the center length- wise. Cut a piece of cardboard 14 in. wide and 14 in . long. Dampen one side with a sponge and lay it on the tape against the crease. Dampen the remaining side and fold over the other wing of the tape. When dry, cut into }:i i n . widths, moisten the g u m m e d

��wings anil insert the sheet to be indexed, |)ressing it down tight. The extended [lortion may be lettered alphabelically or otherwise, accor<ling to indiviilual taste and the use to which it will be put.

While this may not look so well as a le.ither index from an artistic viewpoint, it will, nevertheless, proxe \ery serviceable .ind the cost of the materials from which it is ni.ide is almost nothing.

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