30 



BULLETIN OF THE 



Table ~D. 



Observations at Little Gull Island, Long Island Sound, August q, r88i, com- 

 mencing at 10 A. M. Thermometer — Dry Bulb, 73°. oq, Wet Bulb, ?j° 

 Fahr. Barometer, 2q.TJ Wind, S.W., force, 3. Cir, Strat. Clouds about 

 the horizon. 



At 4 P. M. two of us went in a row boat to Little Gull from the 

 steamer which lay to her anchor half a mile off, and verified the 

 fact that the fog-signal had been in full operation during the time 

 of our observations by the report of the steamer's mate, who had 

 been left there for that purpose. It then occurred to us to investi- 

 gate still more closely what appeared to be a space — a circle of 

 silence — in which we had, during the experiments of the morning, 

 failed to hear the signal. After having had the siren put in full 

 operation again, we pulled toward the nearer end of Great Gull 

 Island, the siren sounding meantime with earsplitting force. When 

 about 600 yards away we suddenly lost the sound as completely as 

 if the signal had stopped. Pulling toward the steamer, not more 

 than 200 yards, we reached a position at right angles with the axis 

 of the siren's trumpet when we suddenly heard the sound "&gain at 

 its full force. Thus, in pulling 500 yards, we passed from com- 

 plete audition of the signal to absolute inaudition ; and then we 

 passed back again to complete audition by pulling 200 yards in 



