Popular Science Monthly 



799 



they have since then come down again. 



The result of this experiment, naturally, 

 was an increased regard for the trench sets. 

 But these were by no means perfect as yet. 



Of course, in addition to the latter, there 

 are automobile sets, aero sets, wagon sets 

 which are used for all moving fighting, and 

 pack sets for the infrequently active cav- 

 alry. But none of these has required the 

 time and attention devoted to the instru- 

 ment used by the infantry. 



As the aerials have to be erected over the 

 trenches, the poles being stuck on the par- 

 apet, they were naturally attractive targets. 



Naturally their operators came in for 

 their share of the snipers' shells. 



In this connection, I would like to tell 

 the story of a friend of mine, Lieutenant 

 L., which will bear out my contention that, 

 when it comes to the scratch, a wireless 

 man can be as cool as the next. 



He was adjusting one of the stays of his 

 aerial pole which had been disturbed by 

 the falling of a shell close by. As he was 

 doing so, over came a second shell, known 

 to the Tommies as a "whizz-bang," which 

 gave him a direct hit, tearing his arm clean 

 away, except for a stump of 4 inches. He 

 looked at it calmly for a couple of seconds. 



"Well, that's a ticket for blighty," he 

 exclaimed then, and fainted. (Blighty, it 

 might be explained, is a Hindustanee word 

 for home which the Tommies have adapted 

 for their own use from the vocabulary of 

 the Indian troops.) 



It was such accidents as this, however, 

 combined with the occasional collapse of 

 the aerial, that convinced the authorities 

 of the need for further experimenting. The 

 officers were now given a more or less free 

 hand to test ideas of their own. 



When I left France, many new devices 

 had already been introduced. From what 

 I hear, they have since been perfected. 



An Easy Way to Wind 

 Sending Helices 



IT IS often very troublesome to wind 

 aluminum or copper wire into a circular 

 form for helices or oscillation-transformers 

 and make a neat job. The following 

 method will be found very satisfactory for 

 the amateur. 



Secure some old lumber 2 in. or more 

 thick and with a compass lay off a circle 

 or circles, which should be smaller in 

 diameter than the diameter of the helix to 

 be made. A good rule to follow is to make 



the diameter of the disk of wood about 

 2 in. less than the finished helix. Though 

 the resulting coil may then be a little too 

 small, this may be easily corrected in 

 assembling the instrument. 



Cut out the disks of wood with a scroll- 

 saw and be sure they are perfectly round. 

 Make a hole in the circumference of each 

 disk just large enough to receive the wire. 

 Bend the end of the wire at a right angle, 

 insert the bent portion into the hole and 

 fasten with a staple. Wind the wire on 

 the drum the required number of turns 

 and allow the wire to remain in this position 

 for a short time, when it may be removed 

 and used. A disk of cardboard cut to the 

 correct size, may be used as a gage to 

 determine whether the helix is kept the 

 right size while assembling. 



Improving the Wireless 

 Aeroplane Set 



THE past year will go down in radio 

 history for the memorable advances 

 which were made in radio communication 

 from aeroplanes — an advance directly 

 traceable to the European war. The 

 lessons taught by the great conflict were 

 not lost upon our Navy Department. As 

 a result, more official encouragement has 

 been given to manufacturers and developers 

 of wireless apparatus in this country than 

 ever before. At the end of 1916, the Navy 

 Department issued requisitions for fifty 

 aeroplane sets. This was the result of 

 three different tests. So successful were 

 the tests that the Navy Department felt 

 itself justified in placing an order for fifty 

 sets at the end of December 1916. 



From the Marconi Company sixteen sets 

 were ordered to be operated on the 500- 

 cycle, quenched spark principle. Nine- 

 teen sets of the audion type were ordered 

 from the De Forest Company. Thirteen 

 Dubilier sets, using the direct current 

 quenched arc, were ordered from the 

 Sperry Gyroscope Company. 



The awards were sufficiently generous to 

 encourage the manufacturers, amounting as 

 they did to about $60,000 altogether. 

 Thanks to the Navy's interest in wireless, 

 we are now far in advance of any European 

 nation in the art of communicating by 

 radio from aeroplanes. We can send twice 

 as far as any other country from the air. 



It is interesting to note the characteristics 

 of the successful sets. The Marconi Com- 



