Figure 63. — Reproduction of BelFs liquid 

 transmitter, his first successful instrument to 

 transmit articulate speech (March 10, 1876). 

 {USJVM 2^2600; Smithsonian photo 4j8j6'.) 



At the end of November they conducted tests on the 

 new device over a 200-mile line running from Boston 

 through Portland, Maine, and back to Salem. They 

 found that some of their sentences could be understood 

 if they shouted although no conversation could be 

 carried on. 



Bell's box telephone pioved to be a better instrument 

 than the one he had demonstrated at the Philadelphia 

 Centennial, but further work was necessary on it, for 

 it still was not ready for commercial use. Its output 

 was weak even when speech was shouted into it. 

 Moreover, the shouting had to be performed in a cer- 

 tain manner — the mouth had to be placed right 

 against the steel diaphragm, and the words properly 

 intoned. Unless these precautions were taken, the 

 sounds emitted from the receiver had to be trans- 

 lated, which Watson did on several occasions. The 

 bo.x telephone reproduced music more successfully 

 than speech. 



On January 13, 1877, Bell applied for a patent on 

 his bo.x telephone, which was granted on January 30 

 as U.S. patent 186787 (fig. 66). Bell's second patent 

 on the telephone became the fundamental one for the 

 construction of receivers, just as the first one became 

 the fundamental patent on the process of transmitting 

 sound by electricity. 



About the time Bell was working on his box 

 telephone, a group of scientists at Brown University 

 in Providence, Rhode Island, began work on this 

 new instrument for communication by electricity.'' 

 During the winter of 1876-1877 and the spring of 1 877, 

 Prof. John Pierce, Prof. Eli Blake, Dr. William Chan- 

 ning, and several others at the university sought to 

 reduce the dimensions of the telephone and to in- 

 crease its efficiency. By April they had made their 

 receiver portable, and by the following month they 

 had evolved the hand receiver with its typical conical 

 mouthpiece having a very shallow cavity between it 

 and the thin iron diaphragm (fig. 67). In back of 

 the diaphragm was a permanent bar magnet on which 

 was placed the inducing coil. The intelligibility of 

 speech as reproduced by the telephone was greatly 

 increased by these changes, and the instrument was 

 no longer so awkward to use. The group of sci- 

 entists at Brown freely donated their modifications 

 of the telephone to Bell without any restrictions or 

 legal claims. Their inodifications assisted Bell in 

 producing the first commercial receiver. After the 

 carbon transmitter had been introduced, the size and 

 structure of this early receiving device remained 

 typical of hand receivers for the next half-century. 



Bell had also been seeking to reduce the size of his 

 box telephone, and about this time he similarly pro- 

 duced a hand telephone.*^ By combining it with the 

 modifications produced by the group at Brown, he 

 was able to place a hand telephone in commercial 

 use in June 1877. 



Once an adequate instrument had been designed, 

 the substitution of the telephone for the telegraph in 

 local circuits spread rapidly. The first commercial 

 telephone line was set up in April 1877 in Somerville, 



51 Walter L. Munroe, "The Brown University 'Experi- 

 menters' and Their Receivers," Brown Alumni Monthly, 1939, 

 vol. 39, pp. 279-282. Two of these instruments were recently 

 donated to the Museum of History and Technology of the 

 Smithsonian Institution {USNM 316078, 316019). 



52 Several of Bell's hand telephones arc preserved in the 

 Museum of History and Technology of the Smithsonian 

 Institution (for example, USNM 251554). 



322 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



