528 EESEARCHES IN SOUND. 



Experiments at Little Gull Island, September, 1875. 



The next series of experiments made dnriug this season was at Little 

 Gull Island, at the east end of Lond Island Sound. This location was 

 chosen on account of its convenience of approach from the harbor of 

 IsTew London, seven miles distant, at which the light-house steamers of 

 the third district usually remain when not engaged in active service, 

 and also because there is a light-house on the island furnished with two 

 sirens of the second order, and an extent of water on every side which 

 would allow the vessels used in the experiments to proceed from the 

 island as a center to a considerable distance in every direction. The 

 island itself is a small protuberance above the water, merely sufficient 

 in area to support a raised circular platform of about 100 feet in diam- 

 eter, on which the light-house and other buildings are erected. The 

 following sketch (Fig G) will give an idea of the position of Gull Island 

 relative to the main-land and the islands in the vicinity. 



From this it will be seen that the position was not the most favorable 

 for a stable condition of the atmosiihere. As the heat of the sun in- 

 creases during the first part of the day, the temperature of the land 

 rises above that of the sea ; and this excess of temperature produces 

 upward currents of air, disturbing the general flow of wind both at the 

 surface of the sea and at an elevation above. But although the locality 

 was unfavorable for obtaining results tending to exhibit the eifects of 

 broad currents of wind flowing in one direction, it had the advantage 

 of ottering more varied phenomena than could otherwise have been ex- 

 hibited. Before commencing the experiments, directions were given to 

 attach a rotating iron neck to the trumpet of one of the sirens, in order 

 that it might be directed to the zenith ; while the other siren remained 

 with its axis in a horizontal direction. The observers in these investi- 

 gations consisted of the chairman of the board; General Woodruff, 

 engineer third district; Porter Barnard, assistant superintendent of 

 construction ; Captain Keeney, and other officers of the Mistletoe; with 

 an assistant who acted as one of the observers and recording clerk. The 

 Mistletoe was daily employed, though on two occasions the Cactus, 

 anotlier of the light-house steamers, rendered assistance. 



