A BELL BUOY TAKEN ON BOARD LIGHTHOUSE TENDKU 

 Shows marine growth and the necessity for periodic cleaning and painting of buoys 



work. The smaller bells are rung by 

 hand. Besides the above, there are vari- 

 ous noise-making buoys ; bells, whistles, 

 and submarine bells are attached to 

 buoys and are made to sound by the 

 movement of the buoy due to the sea. 



There are also used abroad several 

 other types of fog signals. The dia- 

 phone, similar to the siren, explosive sig- 

 nals, consisting of a tonite or other ex- 

 plosive fired from the top of a mast, and 

 recently there has been installed, experi- 

 mentally, at several light stations in 

 France apparatus for sending signals by 

 wireless telegraphy, and a compass has 

 been invented which from a vessel will 

 give the direction of the sending station. 



Nearly all fog signals excepting those 

 on buoys are operated to sound a charac- 

 teristic signal so that they may be distin- 

 guished, there being a succession of 

 blasts or groups of blasts or strokes at 

 regular time intervals, which are made 



known for eacii station. Even adjacent 

 buoys are differentiated by the use of 

 whistles and bells and by variation of 

 tone. 



A first-class fog-signal station requires 

 powerful and expensive machinery and 

 skilled attendance. Such a station may 

 have duplicate engines of 20 horsepower 

 each, and the signal may consume 100 

 cubic feet of free air per minute. 



While aerial fog signals furnish a very 

 valuable aid to navigation under weather 

 conditions when assistance is most 

 needed, yet they are far from the ideal 

 of perfection. Sounds are transmitted 

 through the air erratically, and some- 

 times within a comparatively short dis- 

 tance of a station the fog signal may be 

 inaudible, while in other directions it 

 may be heard for long distances. This 

 is due to the effect of the adjacent land 

 or to conditions in the atmosphere, the 

 sound beiiifr reflected or the sound waves 



49 



