32 



BULLETIN OF THE 



registered only half a degree more of heat at its highest point than 

 it had done in the pilot-house. The course the kite took showed 

 no difference between the air currents alow and aloft. 



Table E. 



Observations at Little Gull Island, Long Island Sound, August 10, i88r, com- 

 mencing at 10:30 A. M. Dry Bulb Thermometer, 76°, Wet Bulb, 75°. 

 Barometer, 29.40. Wind, W. by N., force 3, and steady throughout. Day 

 clear and beautiful. 



The Light House Board has known from the first that aberra- 

 tions in audibility might occur near any fog-signal. When the 

 fog-trumpet was set up at Beaver Tail Point in 1856, the Naval 

 Secretary of the Board, then Lieutenant, now Eear Admiral Jen- 

 kins, U. S. N., in company with Mr. Daboll, its inventor, found, in 

 returning to Newport, that they lost the sound of the signal be- 

 tween Beaver Tail and Fort Adams, and recovered it again between 

 the Fort and Newport, as did later observers, and that this failure 

 to hear it did not result from any failure of the signal to operate. 



The Board's publications show that Prof. Henry, its scientific ad- 

 viser, had the subject for many years continuously under advise- 

 ment, and that between 1865 and 1878, many experiments were 

 made, and various reports on them were submitted to the Board, as 

 to the use and value of its several kinds of fog-signals. In 1870 

 the Board directed General Duane, of the U. S. Engineers, then 

 and still in its service, to make a series of experiments to ascertain 

 the comparative value of its different signals. In his report the 

 General said, speaking of the steam fog-signals on the coast of 

 Maine : 



