532 



RESEAECHES IN SOUND. 



It appears from Table 1 tliat without a single exception the duration of 

 the sound was greater at the top of the tower than at the bottom, al- 

 though the difference in favor of the top of the tower in the several experi- 

 ments is very variable. These results are in accordance with what was 



anticipated. 



Table 2. — Sound tvith the tvind. 



Date. 



September 2 

 3 

 4 

 4 

 6 

 7 



Mean . 



Heard at 

 top of 

 tower. 



mm. sec. 



30 00 



IG 30 



21 00 



18 00 



12 30 



6 30 



17 25 



Heard at 

 foot of 

 tower. 



min. sec. 



30 00 



18 00 



20 30 



23 30 



12 30 



5 30 



IS 20 



In these observations the duration of the sound at the bottom and top 

 are nearly the same, froih which we might infer that the elevation of 

 the observer has little effect on the hearing of sound moving with the 

 wind. Were it not for the result of the first experiment of this class at 

 Block Island, we should not hesitate to adopt this as a general conclu- 

 sion. 



Table 3 — Sound heard nearhj at right angles to the wind. 



