634 



Popular Science Monthly 



In actual operation the sending station 

 mechanically rotates its switch and sends 

 its dots as continuously as a lighthouse 

 with a rotating lantern flashes out beams 

 of light. But there is a short stop before 

 each new rotation, which commences with 

 the first dot flashed by the north-pointing 



Intersecting lines from sending stations tell 

 a Zeppelin commander his position accurately 



antenna. During this short stop an- 

 other but different signal is sent — a non- 

 directional signal which is flashed over 

 all the antennae and which is heard 

 clearly and loudly in any direction. This 

 signal identifies a station by giving its 

 name or its number and supplies the in- 

 formation that in another moment an- 

 other cycle of dots will be sent out 

 toward east, south, and west, commencing 

 at the north. The aircraft commander 

 thereupon sets the hand of his stop watch 

 to the north. He may press the starting 

 button as soon as he hears the first dot, 

 and the stopping button as soon as he 

 hears the weakest dot, or he may press the 

 button at the strongest dot. In actual 

 practice, he pushes the button at the dot 

 immediately following the weakest (or 

 strongest) signal. The difference in loud- 

 ness is considerable from dot to dot. 

 Indeed, the loudness progresses or de- 

 creases around the circle of the compass, 

 depending upon the direction in which one 

 reads. 



Imagine what a sensation it must be to 

 be up in a Zeppelin high over an impene- 

 trable cloud bank, the sky overhead 

 obscured by the bulk of the gas bag, and 

 for these reasons all the laiulinarks by 

 which a man ordinarily locales himself 

 obscured. Yet from somewhere beyond 



the clouds beneath comes that clear radio 

 call indicating that in this direction at 

 least lies a home station. The beacon is 

 welcome. All the Zeppelin commander 

 needs to do now is to tune a bit differently 

 and go through the same performance 

 with another automatic station. In a 

 minute or two he has read on his 

 stop watch dial his direction rela- 

 tive to two different stations 

 whose identity he knows. Drawing 

 lines in these two directions from 

 the locations of these stations on 

 his map, he sees his own location 

 plainly marked on the same map at 

 the point where both lines intersect. 

 More he could hardly demiand. 

 But he may repeat the procedure 

 many times in order to check up 

 his location as frequently as the 

 rapid progress of his craft demands. 

 In peace time the range was in- 

 tentionally cut down to fifty miles 

 in order to prevent interference 

 with regular wireless traffic. But 

 in war, especially during a raid, a vastly 

 greater amount of current may pass 

 through the switches and the antennae 

 may be worked to full capacity. 



Although the Zeppelin's long range 

 Telefunken compass uses the same theo- 

 retical principles as the Bellini-Tosi 

 method; that is, that parallel aerials 

 result in loudest signals, the Bellini-Tosi 

 method is apparently ill- adapted to Zep- 

 pelins. The Telefunken plan seems prob- 

 ably the one universally used. 



Fishing Electric Wires Through Tubes 

 in Fixtures 



WHEN fishing wires through a fix- 

 ture, which has a sharp angle, a 

 piece of chain A from a pull chain socket 

 can be used to good 

 advantage. If a 

 wire is used it may 

 get caught at point 

 B, while the flex- 

 ible chain readily 

 passes around this 

 bend. A strong 

 cord can then be 

 attached to the 

 wire which is easily 

 drawn through the 

 fixture. 



A chain pull used 

 to draw wire into 

 electric fixtures 



