932 



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 i3''2 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 



IS 



t^ 



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- 



C. A.NUERSON. 



c 



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. 



