RESEARCHES IN SOUND. 



Fig. 9. 



Caotvs 

 /fj/i- course 



537 



2«ci course 



As affording- evidence in support of this hypothesis, it may he men- 

 tioned that on examining the records of the Signal-Service, of which there 

 is a station at ]S"ew London, seven miles north of the position at which 

 these observations were made, it was found that the wind in the morn- 

 ing of that day was south, in the afternoon southwest, and in the even- 

 ing northwest, and that it was lU'obable, as in other cases, that the wind 

 had changed above while the part of the course h c was run. 



Experiments of September 6. — Barometer, 29.93 inches ; thermometer, 

 dry bulb, 74o.5 F. wet bulb, 07°; wind from northwest to southwest, 

 seventeen miles per hour. The wind, though of higher velocity than on 

 any other occasion, was variable. On this day the experiments were 

 principally made with the Mistletoe. The Cactus, being obliged to leave 

 on other duty, ran one course a distance of two-thirds of a mile before 

 the sound of her whistle was lost at the light-house. She afterwards 

 steamed off in the direction C h (Fig. 10), noting the sound of the siren, 

 which was lost at the point &, afterward regained, and heard distinctly 

 ten and one-half miles distant. 



During the passage of the first course of the Mistletoe, the wind at 

 the surface and above was from southwest, the latter being indicated 



