826 The Outline of Science 



tude as the loss of the Titanic in 1912 with over 1,500 lives could 

 take place. Even then, 711 passengers in the ill-fated liner owed 

 their lives to wireless, but had that unfortunate maiden voyage 

 been made to-day probably the great liner would have received 

 timely warning of her danger; cruising about in the North 

 Atlantic, there is now an Ice Patrol on the lookout for icebergs, 

 the exact position and size of which is broadcasted to all ships 

 in these northern waters twice a day or oftener. The expense 

 of maintaining this patrol is borne proportionately by all the 

 maritime nations using the Atlantic. In connection with the 

 warnings which wireless gives of the presence of icebergs in a 

 particular place, it is interesting to note that it is to electricity 

 also we owe the detection of icebergs. It is not always the case 

 that the temperature of the water indicates the presence of an 

 iceberg; the temperature test is not always reliable. Icebergs 

 which are broken-off ends of glaciers are formed from fresh water 

 and affect the salinity or saltness of the sea-water around them. 

 The "Salinometer" is an apparatus which applies an electrical test 

 for detecting differences in the salinity of sea-water. 



All over the world there are to be found a vast number of 

 land wireless stations; some are coast stations for intercommuni- 

 cation with ships at sea, others are very high-powered radio-sta- 

 tions for long-distance transmission. There is a station, for 

 example, at Lyons in France, for communication with North 

 Africa, and it is of such high power that it is capable of reaching 

 as far as Indo-China, which is 5,000 miles away. 



It was a great feat when the first wireless signals were 

 transmitted across the Atlantic; the first official messages crossed 

 the Atlantic on December 16, 1902, the signals being sent from 

 the station at Poldhu in England to Glace Bay in Canada. 



Twenty years later we find the world covered with gigantic 

 power-stations for transmitting half round the world electro- 

 magnetic waves of immense energy for telegraphic purposes, 

 employing thousands of horse-power and exhibiting in every 



