52 THE OCEAN 



heard for some distance. This is not, how- 

 ever, a very reliable means of locating ice, 

 for a berg may or may not give an echo ac- 

 cording to w^hether or not its sides are steep 

 and perpendicular or the face of the ice is 

 turned towards the sound or is slanting or 

 oblique. Experiments by the ice-patrol boats 

 prove that fully ninety per cent, of the at- 

 tempts to locate bergs by sound are without 

 result and that it is practically impossible to 

 get an echo from a berg more than half a 

 mile distant and, moreover, the echo when it 

 does occur may be misleading. In one case, 

 recorded by the ice patrol, an echo was ob- 

 tained when the ship was between two masses 

 of ice, one a so-called "growler," or piece 

 broken from a berg, and the other a large 

 berg; and as events proved the growler gave 

 forth an echo, whereas the berg gave none. 

 Many sailors depend for a warning against 

 bergs largely upon the temperature of the air 

 or water and the ''feel of ice" in the air, but 

 from the experiments and experiences of the 

 Government boats such methods are very unre- 

 liable. In fact the officers of the ice-patrol 



