Popular Science Monthly 



635 



To Change a Gas Lamp into an 

 Electric Light 



TO cliangc from gas to electric liglu 

 on motorcycle headlights and retain 

 the convenience 

 of both, all thai is 

 necessary is to 

 solder a cande- 

 labrum socket to 

 the old burner. 

 Care should be 

 taken to have the 

 burner just the 

 right height so 

 that the lamp can 

 be focussed prop- 

 erly.— F.G. Daly. 



Best Wavelengths for Certain 

 Distances 



IT has been figured out that for sending 

 700 kilometers the best wavelength is 

 only 275 meters, in so far as the condi- 

 tions between the two stations are 

 concerned. For 1000 kilometers, the 

 best wave is about 560 meters long, and 

 for 1500 kilometers about 1250 meters. 

 This computed result may be greatly 

 modified by the characteristics of the 

 sending and receiving antennas, however. 



Lighting an Oil- Stove with an Alarm- 

 Clock on Cold Mornings 



NO one really enjoys getting out of 

 lied on a cold morning before the 

 room is heated. And it is not really 

 necessary; for with an oil-stove, an 

 alarm-clock, a spark-coil (a 3<t-in. coil 

 is sufficient), an old bell, some spring- 

 brass, binding-posts and wire, an ar- 

 rangement can be made to obviate it. 



Tiie oil-stove, with the hood turned 

 back to expose the burner, is shown in 

 Fig. I. The wire may be ordinary 14- 

 gage, asbestos-covered. The principal 

 thing to be observed is that the distance 

 from the wire A to the burner B is less 

 than from the wire to the Hue C (which 

 comes down and covers the burner); 

 otherwise the. spark would jump from 

 A to C, instead of through the wick to 

 B. This distance is best determined 

 by experiment. Over the wire A is 

 a tin strip F, soldered to the tank to 

 hold the wire in position. The connector 



E may be removed by loosening the 

 connecting screws; this permits taking 

 out the tank without disturbing the 

 spark-wire. Grounded to the frame of 

 the stove is a binding post D. 



The alarm-clock is mounted on a 

 small board, as shown in Fig. 2. Have 

 the brass springs sufficiently heavy and 

 far enough apart to permit the key, when 

 turning, to be held by the bend at the 

 top of the spring. The important part 

 of the mechanism is the relay, which 

 turns off the current when the stove is 

 lighted. A buzzer or an old door-bell is 

 shown at A, Fig. 3, with the hook B 

 soldered on to the end of the armature. 

 A piece of sheet metal C is bent snugly 

 around the screw H, which has a shoul- 

 der filed in it to prevent C from lying 

 on the board. A piece of brass, D, is 

 bent as shown, with a hole drilled for the 

 screw E, which adjusts the tension of 

 D on C. The spring F tends to pull C 

 to the stop G out from under the spring 

 D. The wiring is shown by dotted lines. 



The action is as follows: The magnet 

 A draws the armature B to its core. 

 This releases the spring C, which slides 

 slowly (its movement is regulated by the 

 screw E) out from under spring /-', 

 causing a sliding contact of a few 



/y.J 



A 



&!ZS.'f! -= 



Induction Coil 



•^ Prmary /Vrrs \ 



To S^iv 



Wiring diagram and connections (Fig. 4) 

 to an alarm-clock for lighting an oil-stove 



seconds' duration, which ends in discon- 

 necting the primary circuit. Dampening 

 the movement of the spring gives the 

 spark time enough to to ignite (he cold 

 oil. — .XRTiitR F. Stilson. 



