1908.] 



on Transatlantic Wireless Tehgrapliy. 



121 



This daily newspaper has now been adopted by nearly all the 

 large Liners plying to New York and the Mediterranean, and it 

 obviously owes its entire existence to long-distance wireless telegraphy. 

 Therefore the tranquillity and isolation from the outside world, which 

 it is still possible to enjoy on board of some ships, is rapidly becom- 

 ing a thing of the past. But, however much travellers may sigh over 

 the innovations which have lately been brought about, they seem 

 anxious enough to avail themselves of the new method of communi- 

 cation on all possible occasions. 



Early in 1905, the construction of the new station at Grlace Bay 

 was sufficiently advanced to allow of preliminary tests being carried 

 out. The aerial was very large, and consisted of a vertical portion in 

 the middle 220 feet long supported by four towers and attached 

 to horizontal wires, 200 in number, each 1000 feet long, extending 

 radially all round, and supported at a height of 180 feet from the 

 ground by an inner circle of 8 and an outer circle of 16 masts 

 (Fig. 11). 



Fig. 11. 



The natural period of oscillation of this aerial gave a w^ave-length 

 of 12,000 feet. 



The capacity employed was 1 * 8 microfarads, and the spark length 

 f inch. 



Signals and messages from this station were received at Poldhu 

 by day as well as by night, but no commercial use of the station was 

 made at that time, in consequence of the fact that although the 

 signals came through by day as w^ell as by night they were exceedingly 

 weak and faint, and also because the corresponding station on the 

 same plan had not yet been erected in Ireland. 



A further step in advance was the adoption at the transatlantic 

 stations of the directional aerial shown in Fig. 12.* The ordinary 

 wireless telegraph aerials, which I have already described, send out 

 electric radiation equally in all directions. This is, however, in many 

 cases a disadvantage. Many suggestions respecting methods for 

 limiting the direction of radiation have been made by various workers, 

 notably by Messrs. Artom, Braun, and Bellini Tosi. 



♦ ' On methods whereby the radiation of electric waves may be mainly 

 confined,' etc. Proceedings of the Royal Society, G. Marconi, A. Ixxvii. 

 1906. 



