272 WIRELESS TELEGRAPHY. 



they have about -io sets of such wireless telegraph apparatus installed. 

 The length of vertical wire of these stations is about 150 feet. The 

 war ships thus equipped have signaled each other when 100 miles 

 apart. The wireless system is also installed at different points on the 

 continents of P^urope and America — at La Panne, Belgium, for exam- 

 ple, and at Dorkum Island in the North Sea off the mouth of the Ems. 



A niun])er of light-ships have also been equipped with the wireless 

 telegraph systems; for instance, the Goodwin Sands light-ship, the Bor- 

 kum light-ship, 25 miles from the island of that name, and the Nan- 

 tucket light-ship, off the Massachusetts coast, from which station 

 passing vessels are daily reported to the mainland. 



Many mercantile steamships have also been equipped with the same 

 sj'stem, notably the Kaiser Wilhelm der Grosse^ of the North German 

 Llo3^d Steamship Company, the DeidscMavd, of the Hamburg-Ameri- 

 can Line, and the vessels of the Cunard Line, and many others. Fre- 

 quently vessels thus equipped have communicated with one another 

 ]>3* wireless telegraphy in mid ocean, and while out of sight of each 

 other, communication being thus kept up for hours while the vessels 

 were passing in opposite directions. 



There is little doubt that the use of wireless telegraph systems by 

 the navies of the world will become general in the near future. There 

 are several reasons why such systems are especiall}" applicable to, and 

 desirable on, war vessels, which depend so largely on signaling. For 

 instance, signaling by the Hertzian waves is more successful over 

 water than over land, greater distances being reached over water. 

 The vessels already carry the necessary masts for the vertical wires; 

 the apparatus, including batteries, does not require to 1)e portable; 

 there is at present no other practicable method of signaling at sea to 

 a distance of even a few miles in foggy or hazy weather. 



With regard to the use of wireless telegraphy for military purposes 

 in actual warfare, the problem is somewhat different and the obsta- 

 cles to its use are considerable. Thus the question of obtaining and 

 transporting the masts for the vertical wires is a serious one. This 

 was one of the difficulties met with in the South African war. The 

 matter of providing in an easily porta])le and reliable form the elec- 

 trical energy reciuired for the operation of the oscillator is also likely 

 to be rather difficult under some circumstances. Should the cjdinder 

 arrangement enq)loyed by Marconi be found suitable for land work, 

 this would be a decided gain, and if by this means a reasonal)le dis- 

 tance, say iT) to 50 miles, could be covered ]»y wireless telegraphy, it 

 would be a very valuable addition to military signaling in the ffeld. 



There is, however, nearly always in land operations the alternative 

 of wire telegraphy, and while the dilliculties of transporting the poles 

 and wires for such systems arc frecjuently very great, they have rarely 

 been found insurmountable, and where this may be the case, as when 



