180 ANNUAL KEPORT SMITHSONIAN INSTITUTION, 1908. 



another method in which the 10,000 cycle alternator above referred 

 to was employed had been developed to such an extent that the appa- 

 ratus could be used practically and sets were advertised and tendered 

 to the United States Government.* The transmission was, however, 

 still not absolutely' perfect. 



By the fall of 1906 the high frequency alternator had been brought 

 to a practical shape and was used for telephoning from Brant Rock 

 to Plymouth, a distance of 11 miles, and to a small fishing schooner, 

 this being the first instance in which wireless telephony was put in 

 practical use. The transmission was perfect and w^as admitted by 

 telephone experts to be more distinct than that over wire lines, the 

 sound of breathing and the slightest inflections of the voice being 

 reproduced with the utmost fidelity. 



As it was realized that the use of the wireless telephone would be 

 seriously curtailed unless it could be operated in conjunction with 

 w^ire lines, telephone relays were invented both for the receiving and 

 transmitting ends, and were found to operate satisfactorily, speech 

 being transmitted over a wire line to the station at Brant Rock, re- 

 transmitted there wirelessly by a telephone relay, received wirelessly 

 at Plymouth, and there relayed out again on another wire line. On 

 December 11, 1906, invitations were issued to a number of scientific 

 men to witness the operation of the wireless transmission in conjunc- 

 tion with the wire lines. A report of these tests appeared in the 

 American Telephone Journal of January 26 and February 2, 1907, 

 the editor being one of the men present. 



In July, 1907, the range was considerably extended and speech was 

 successfully transmitted between Brant Rock and Jamaica, Long 

 Island, a distance of nearly 200 miles, in daylight and mostly over 

 land,^ the mast at Jamaica being approximately 180 feet hi^h. 



In 1907 several European experimenters succeeded in transmitting 

 speech wirelessly, using some of the earlier forms of the writer's arc 

 method, and some months ago the vessels of our Pacific squadron 

 were equipped with wireless telephones, using this arc method, by 

 another American company. 



METHODS AND APPARATUS. 



Methods and Apparatus for Producing the Electromagnetic 



Waves. 



These have been already referred to. Plate 5, figure 2, shoAvs a 

 rotating spark gap giving approximately 20,000 discharges per sec- 

 ond. This was connected to a 5, 000- volt source of direct current. 



« Letter of July 8, 1905; see The Electrician, London, February 22, 1907; also 

 catalogue of 1904 and subsequent. 



^ " Long distance wireless telephony," The Electrician, October 4, 1907. 



