EESEARCHES IN SOUND. 



533 



From the result of this table it would appear that the sound can be 

 heard moving at right angles to the wind better at an elevation that at 

 the surface — a result not anticipated. 



OBSERVATIONS ON TUE EFFECT OF WIND ON SOUND. 



This series was commenced on the 2d of September. Barometer, 30.3 

 inches ; thermometer, dry-bulb, 70o.5 F. wet-bulb, G7o.5. Wind at the 

 surface of sea was six miles per hour, and variable ; at 3 i>. m. the ve- 

 locity was eight miles at the surface. (See Fig. 7.) 



Fi". 7. 



1^^ course 



The experiments were made by means of the steamer Mistletoe, which 

 proceeded from the light-house, as a center, in different directions, 

 blowing the whistle every half-minute, and returning when, from a sig- 

 nal, the sound was lost ; the time being noted by different observers, 

 and the distance estimated by the position of the steamer in reference 

 to known objects on the Coast-Survey chart, as well as by angles of 

 azimuth and time of sailing. The steamer was directed to proceed, as 

 indicated in Fig. 7, 1st, against the wind, so that the sound would come 

 to the observers with the wiud ; 2d, at right angles to the wind ; 3d, in 

 an intermediate direction between the last course and the direction of 

 the wind ; 4th, approximately with the wind, so that the sound would 

 come to the ears of the observers against the wind ; 5th, in an interme- 

 diate direction j and, 6th, again at right angles to the wind. It was 



