TELEPHONE 



5741 



TELEPHONE 



transmitted more accurately than the sounds of 

 the voice. The complete set is made very light 

 and compact. On a war vessel the com- 

 mander is in telephonic communication with 

 every part of the ship. The instruments are 

 made very substantial, to withstand the shocks % 

 to which they are subjected, some being bullet 

 proof. 



The helmets of divers are fitted with trans- 

 mitters so that the diver is In communication 

 with the boat above. 



' For railway service a telegraph line may be 

 made to serve as a telephone line. The tele- 

 phone is extensively used in train dispatching, 

 its advantage over the telegraph being greater 

 speed and the fact that it does not require a 

 trained telegraph operator to serve as train dis- 

 patcher. Telephone sets are installed at sid- 

 ings, crossings, water tanks and other similar 

 places so that a train crew may, in case of 



emergency, communicate quickly with the train 

 dispatcher. Many railroads, in addition to the 

 dispatching circuit, install also a message cir- 

 cuit and frequently a block line for communi- 

 cation with the operators of interlocking 

 switches and block signals. 



Another important branch of the telephone 

 industry is the private exchange, in reality a 

 telephone system under private control. Some 

 private exchanges possess more telephones on 

 their lines than are required to care for the 

 business of cities of considerable size. Every 

 large business house has its own private ex- 

 change for communication between the various 

 departments of the house. As a rule these pri- 

 vate exchanges also connect with the public 

 exchange so that any department may make 

 either a local city call or a long-distance call 

 through the private exchange, just as over an 

 ordinary telephone. 



Brief History of the Telephone 



Soon after the invention of the Morse tele- 

 graph, the idea of "talking by telegraph" began 

 to grow in the minds of inventors. The out- 

 growth of this idea was the modern telephone. 

 The telephone which was first patented and 

 first exhibited to the public was that of Alex- 

 ander Graham Bell. His patent, dated March 

 7, 1876, was for "certain new and useful im- 



THE FIRST BELL TELEPHONE 



provements in telegraphy." One of these "im- 

 provements" was "the method of transmitting 

 vocal and other sounds by telegraphy." In the 

 Bell telephone the transmitter and the re- 

 ceiver were constructed on the same principle 

 as the receiver of the modern telephone. Each 

 receiver had a piece of parchment tightly 

 stretched over a circular frame and a piece of 

 soft iron fastened to the center of the parch- 

 ment. An electromagnet within the frame was 

 placed with one end near, but not touching, the 

 parchment. 



The Bell telephone was first exhibited to the 

 public at the Centennial Exposition in Philadel- 

 phia in 1876, and the new invention was re- 

 ceived with incredulity and ridicule. Bell was 

 called "a crank who says he can talk through 

 a wire." He had to prove the worth of his 

 invention. To do this he borrowed a telegraph 

 line in Boston, having a length of two miles, 

 and with a friend held a conversation over the 

 wire, the first sustained conversation by tele- 

 phone, and the report of this conversation was 

 published in a Boston newspaper. Soon after 

 this Bell lectured in Salem, and a report of the 

 lecture was sent by telephone to the Boston 

 Globe, the first news transmitted by telephone. 

 This aroused public interest, and in the follow- 

 ing year (1877) the telephone business made a 

 beginning. 



In May, 1877, a young man named Holmes, 

 who installed burglar alarms in business houses 

 in Boston, borrowed five telephones and set 

 them up in five banks, connecting them to the 

 wires of the burglar alarm. The five telephones 

 could be connected by a switch in Holmes' 

 office. This was the first telephone exchange; 

 it was a crude affair compared with a modern 

 exchange. In the same month a man named 

 Emery leased two telephones, paying twenty 

 dollars, the first money transaction in the tele- 

 phone business. From this small beginning 

 the business grew until, in August, 1877, there 

 were 778 telephones in use. But this was in- 

 significant for such an important invention as 



