WIRELESS TELEGRAPH 



G320 



WIRELESS TELEGRAPH 



j Known Wireless Telegraph Commercial Station5^jjj\\l9f7 



THE STOW OF WIRELESS TELEGRAPHY 



IRELESS TELEGRAPH, tel'egraj, 

 an invention which many scientists rank as the 

 greatest marvel of inventive genius, with the 

 possible exception of the wireless telephone. 

 Its name properly defines it. It is an electric 

 telegraph which has no connecting wires be- 

 tween sending and receiving stations. The 

 electric impulse travels through the air in 

 every direction. There is not the secrecy pos- 

 sible that can be commanded in messages over 

 telegraph wires, for within a given radius any 

 receiving instrument "tuned" to receive wave 

 impulses of certain lengths can catch a wireless 

 message. This is explained later in the present 

 article. This unavoidable publicity is over- 

 come in necessary cases by the use of code 

 words which mean nothing to persons who can- 

 not interpret them. 



Perfection in mechanism, which has resulted 

 in extending the area of communication, has 

 been very rapid. The earliest wireless device 

 could send messages but a few miles, and then 

 only under most favorable weather conditions. 

 When the first "wireless" connection was made 

 across the narrowest part of the Atlantic, be- 

 tween Newfoundland and Ireland, less than 

 2,000 miles, the world marveled; to-day one 

 would not be surprised at the announcement 

 that powerful impulses have been transmitted 

 around the world. Already messages from 

 Alaska have been "picked up" at Key West, 

 Florida, under very favorable conditions, and a 

 dispatch from Hawaii has been read at the 

 powerful station at Arlington Heights, opposite 

 Washington, D. C. The average range for 

 equipment of the first class, however, is not 

 greater than 1,000 to 1,500 miles. Many instru- 



ments will not "carry" farther than 100 miles. 

 (See comment, with illustration of Arlington 

 station, in this article.) 



That the art of wireless telegraphy is easily 

 mastered is shown by the fact that not only 

 men but thousands of boys not over eighteen 

 years of age have installed systems in their 

 homes and have become expert operators. 

 When the War of the Nations involved the 

 United States, in April, 1917, the government 

 was obliged to order all private systems dis- 

 mantled in order that official secrets might not 

 reach enemy sympathizers. It was found that 



SIMPLEST PRACTICAL TRANSMITTER 



(1) Key (6) Ae'rial 



(2) Induction coil (6) Copper plate in 



(3) Spark gap ground 



(4) Battery 



nearly 200 private stations existed in Chicago 

 alone. 



Description of Equipment. The simplest 

 form of wireless telegraph sending equipment 

 consists of an induction coil (spark coil) with 



