634 



Popular Science Monthly 



A Combination Front and Back 

 Door Alarm-Bell 



FASTEN a common alarm clock on a 

 block of wood, after removing the 

 bell and legs. The block must be cut 

 out to expose the back of the clock so 



Diagram of the wires for alarm in connection 

 with the front and back door bells 



it can be wound. Two strips, about 4 

 in. wide, hold the block from the wall 

 for this purpose. Three light angle 

 strips hold the clock to the board. In the 

 upper corner of the board place the con- 

 tact hook, loosely pivoled and sui>ported 

 by a small brad driven into the board. 



When the alarm is released the ham- 

 mer makes contact with the hook, closing 

 the bell circuit. This bell will ring 

 until the hook is thrown back. The con- 

 nection t(j the door-bells are ordinary. 

 Partially run-down batteries from an 

 autoniol)ile may be used for this ar- 

 rangement, connecting a sufficient num- 

 ber in series to ring through the bell 

 circuit. 



Insulating and Decorative Enamel for 

 Electro-Magnets 



IN half an ounce of wootl ali-ohol dis- 

 solve one small stick of colored seal- 

 ing wax; shake thoroughly at regular 

 intervals to facilitate comjilete dissolu- 

 tion; put mixture in a tightly corked 

 test tube ur small vial. This mixture 

 will keep indehnitely, and may be ap- 

 plied with a small (-amcl's hair brush. 

 Shake tube well before using. 'I'his is ,1 

 (|iii( k drying and lustrous cniiiu'l. 



Electric Burner for Making Storage- 

 Battery Connections 



IT is well to have all connections on 

 storage batteries fastened to the 

 binding posts in a permanent way by 

 soldering or lead burning. To do this 

 work properly requires an oxygen burner, 

 but the layman is not always sufficiently 

 familiar witli the use of this gas to make 

 the proi)er ajijilication, and the appa- 

 ratus is a rather expensive one to keep 

 on hand. 



The current taken from the cell is suffi- 

 cient for the heat element and it is only 

 necessary to make connections as shown 

 in the illustration. Almost any par- 

 tially experienced person can fasten the 

 connecter by lead burning. 



To produce the proper amount of 

 heat, an old carbon taken from an arc 

 lamp is filed down to a small point to 

 reduce the cross section area and is 

 used the same as a soldering iron. The 

 carbon is fastened to one terminal 

 binding post of the battery with a large 

 wire, using a jMcce of sheet brass around 

 the carbon to make a better connection. 

 Clean the binding post thoroughly to 

 make a good weld. The carbon held on 

 the binding jjost as shown (juickly heats 

 it to a point that will melt the lead; 

 then the carbon is used in the same way 



The current token from the cell is sufficient 

 to weld the connections to tlie binding-jxists 



• IS .III ordinary soldi-ring iron in making 

 a good union ot I he |)arts. 



