952 



Popular Science Monthly 



most used letter in the alphabet, is rightly 

 given the shortest Morse signal; T being 

 the next letter in order of frequency is 

 awarded the next shortest signal, and so on, 

 until we find Z, the least employed letter, 

 deservedly saddled for its laziness with one 

 of the longest Morse signals. 



But by Mr. Morse's allocation of English 

 letters, as will be seen on reference to 

 column five of the diagram, only 14 out of 

 the 26 letters are correctly suited. This 

 means great loss of time in transmission. 

 It may be observed in this connection that 

 the Morse code is in use on no less than 95 

 per cent, of the telegraph lines of the world. 



It seems almost a pity that advantage 

 was not taken of the advent of wireless 

 telegraphy to redistribute the Morse sym- 

 bols on the ideal basis here demonstrated. 



Making a Good Outdoor Ground 

 for Wireless Apparatus 



THE outside ground wire for the wireless 

 set or other experimental apparatus of 

 the amateur is continually meeting with 

 misfortune. No ordinary joint seems capa- 

 ble of permanency. This is usually due to 



The old and the new methods of making a 

 permanent ground for electrical apparatus 



inconvenient locations, especially in crowded 

 cities where the shed or "shop" is likely to 

 be next to an alley fence or in a similarly 

 exposed place. 



In our usual thoughtless following after 

 precedent we are likely to believe that the 

 standard grounding joint customarily em- 

 ployed by telephone and electric lighting 

 companies is about the only grounding joint 

 possible. Consequently every time the 

 ground wire gets stripped off its pipe, we 

 replace it with another of exactly the same 

 sort. This usual grounding joint is shown 

 in the illustration. It consists simply of 

 the groundwire wrapped several times 



around the pipe that goes down into the 

 earth, the turns being held in place by oc- 

 casional dabs of solder. Naturally this ar- 

 rangement is not very strong mechanically. 



A more satisfactory joint can be made as 

 follows: Take a round file and brighten up 

 the interior of the pipe at the end; then 

 wet some waste and tamp it down into the 

 pipe a distance of about \\i in. Bunch up 

 the end of the ground wire until it fills most 

 of the space above the waste ; then heat the 

 end of the pipe and the bunched-up wire 

 with a soldering torch, at the same time 

 applying a little soldering paste, in order 

 that the solder to come may stick easily. 

 When the end of the pipe becomes hot 

 enough to take the solder readily, apply 

 enough of that material to completely fill 

 the end. This process will naturally en- 

 tirely submerge the bunched-up wire. 

 With a cloth, round off the upper surface of 

 the solder while it is still warm, until it 

 forms a neat cone, with the ground wire 

 coming out of the center as shown in the 

 illustration. 



This sort of a ground connection buries 

 the end of the wire inside the pipe, instead 

 of causing it to cling to the exterior as best 

 it can, as with the old way. The end of the 

 pipe may be subjected to very rough treat- 

 ment indeed, without disturbing the wire. 



Auto-Transformer in Headlight 

 Circuit on a Magneto 



HEADLIGHTS from the Ford magneto 

 are so wired that when one of 

 them burns out the circuit is broken and 

 the other one goes out. This trouble may 

 be easily overcome by the use of a small 

 auto-transformer. Such a transformer 

 may be made in a rectangular form from 

 thin strips of sheet iron }/% in. wide, cut 

 in lengths to make four piles 1 in. high, two 

 of which are 1^2 m - long and the other two 

 2Y2 in, long. These are all given a coat of 

 shellac varnish and allowed to dry; then 

 they are built up in dovetail fashion 

 after the coils are placed on one of them. 



Make two coils of 120 turns each, using 

 No. 20-gage wire — about % lb. will be re- 

 quired. The method of placing the coils on 

 the core and the necessary wiring are illus- 

 trated. Should the device fail to work 

 satisfactorily, reverse the connections of the 

 coils. With this outfit, the burning out of 

 one headlight will not cause any percepti- 

 ble change in the light from the other. It 

 is also possible by winding another coil on 



