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Then heat the tip to a cherry red and hit 

 it a sharp blow with a hammer to flatten 

 it sHghtly, and quickly dip into cold 

 water. This gives about the proper de- 

 gree of hardness. The necessary clear- 

 ance was given when it was flattened, 

 and the point is then ground down until 

 the flat side is very nearly a half-round 

 and the narrow side tapers to a point at 

 an angle of 30 degrees. The other end 

 is filed off slightly on a long angle, as 

 shown in Fig. 4. This slides up upon 

 the slot in the chuck and prevents the 

 drill from turning. 



The bow is made of some limber 

 wood, such as elm or hickory, and is 

 trimmed down so that when bent it will 

 give the desired tension to the string. 

 This depends on the wood used and 

 should be sufficient to keep the cord from 

 slipping when twisted once around the 

 spool. The bow used with the drill de- 

 scribed was 2.y-z feet long, ^ inch wide 

 and J4 inch thick. The cord should be 

 of leather attached to one end and about 

 6 inches above the other end, which was 

 left for a handle. 



The chuck described here is expressly 

 made for the wire drills, but if the 

 maker has any other drills that bore with 

 a backward and forward motion, he 

 could use any design of chuck he wishes 

 in order to accommodate the drills. 



This bow-drill, if the points are well 



Popular Science Monthly 



ground, will quickly bore wood or iron 

 and if supplied with turpentine will even 

 bore glass. When needed, the drills can 

 be made longer, but when the length is 

 over 6 inches care must be taken or they 

 will bend when pressure is exerted on 

 the handle. To rotate the drill, the bow- 

 string is twisted once around the spool 

 and the bow is then pushed rapidly 

 backward and forward at right angles to 

 the handle. — Rae McGooch. 



An attractive non-upsetting ink bottle stand 



'_-- The bottle will 

 glow with the 

 sparks which fill it 



The Luminous Bottle 



TO perform this experiment, fill a 

 big bottle nearly full of water and 

 run a wire from one terminal of a spark 

 coil to the inside of the bottle. Set the 

 bottle on a plate of glass to insulate it 

 from the table. Then run a wire 

 from the other terminal and tie 

 it securely around the bottle about 

 half way up. When the spark- 

 gap is started, little sparks are 

 given off from the wire to form 

 a fine network all about the bot- 

 tle. — F. M. Kimble. 



Non-Upsetting Holder for 

 Drawing Inks 



AN ink stand that will not up- 

 L set, owing to the broad base 

 secured, can be made according 

 to the dimensions given in the 

 diagram. The base should be cut 

 first and the sides fitted after- 

 wards. Cigar box wood will do. 

 The two end pieces should pro- 

 trude in front of the bottles and 

 the upper surfaces should be 

 whittled out for pens. 



I 



