Popular Science Monthly 



Keyless Lamp Socket for Switching 

 Electric Currents 



THE well known key socket for electric 

 lamps requires at least thirty separate 

 and distinct pieces, the assembling of which 

 is an important item in estimating the cost 

 of production. 



A new socket has been devised which may 

 be made of less than half the usual number 

 of parts. Instead of having a key the 

 bulb itself serves to switch the current on 

 and off. 



Pushing the bulb inward about a quarter 

 of an inch causes a spring finger to snap in- 

 to contact to connect one side of the circuit, 

 while the central contact point of the lamp 

 is caused to engage with the terminal of 

 the other side of the circuit, thus turning 

 on the current without a push button or 

 switch lever. 



In order to cut off the light, the lamp is 

 drawn back so 

 as to sever the 

 connections, 

 the act of push- 

 ing in or draw- 

 ingout the bulb 

 being far less 

 injurious to the 

 threaded end 

 of the socket, or 

 to the fixtures, 

 A part tarn of the socket than the turn- 

 awitches the current on or off |ng operation 



of the key. 



The drawing shows the socket made of 

 two parts, the lower end, which is threaded 

 to receive the lamp, being adapted to slide 

 within the upper portion that is attached to 

 the fixture. An upwardly-projecting spring 

 finger, the lower end of which is attached to 

 the inside of the lower shell, has its V- 

 shaped upper end normally resting within 

 a recess formed through the insulating 

 material, so that when the bulb is pushed 

 upward the V-shaped end is caused to 

 snap over and engage with one terminal, 

 while a spring finger on the opposite side of 

 the insulating block contacts with the 

 central terminal of the bulb. 



It will be observed that by this arrange- 

 ment both terminals are out of the circuit 

 when the electricity is cut off. By loosen- 

 ing the two screws which hold the shells 

 together the entire working parts may be 

 withdrawn, together with the insulating 

 block, affording a convenient and readily 

 accessible means for attaching or repairing 

 the wires. — J. S. Zerbe. 



151 



Curious Circuit for Audion On a 

 Wireless Set 



IT has often been said that it is not 

 possible to use an audion bulb in con- 

 nection with a simple double slide tuner. 

 But experiment has proved that a 

 hook-up may be tuned very closely 



Diagram showing an audion bulb in con- 

 nection with a simple double slide tuner 



and accurately, the strength of signals from 

 all stations being much greater than when 

 the same audion is used with a receiving 

 transformer. On a single-wire aerial 50 ft. 

 high and 150 ft. long, the time signals from 

 Arlington were received over 500 miles 

 under all weather conditions. As will be 

 recognized by those familiar with vacuum 

 bulb circuits, the arrangement shown is 

 very different from the normal arrange- 

 ments on the usual wireless set. 



Conversion of Kilometers to Nau- 

 tical and Statute Miles 



WIRELESS telegraph transmission dis- 

 tances are often stated in kilometers, 

 nautical miles or statute miles. To convert 

 the number of kilometers to nautical miles, 

 multiply by fifty-four and point off two 

 decimal places. To convert from kilometers 

 to statute miles, multiply by sixty-two and 

 point off two places. If the distance is 

 given in statute (or land) miles and you 

 want it expressed in kilometers, multiply 

 the number of miles by 161 and point off 

 two decimal places. 



An Experimental Wireless Aerial 

 Made of Zither Strings 



WHILE experimenting with several dif- 

 ferent types of novel aerials I found 

 that by connecting together all the strings 

 of a zither and substituting it for the aerial 

 with an inductive coupler, fixed condenser, 

 silicon detector and a pair of 2000-ohm 

 telephones, I could hear a number of local 

 stations very clearly. — Yk Drobe. 



