466 WRinNGs OF Joseph henry. [1875 



while the Mistletoe continued to hear the whistle of the 

 Putnam ten minutes longer. Owing to a mis-understanding, 

 one of the steamers stopped for two minutes and then re- 

 sumed its course. As both steamers were separating during 

 the first two minutes with equal speed, the distance of the 

 sound heard moving against the wind is represented by 4, 

 while the sound was heard with the wind through a space de- 

 noted by 2 X 10 + 4—2=22, ttie ratio being 1 : 5J. 



Fourth experiment. — The vessels again changed directions, 

 the Putnam going with the wind and the Mistletoe in the 

 opposite direction. The Mistletoe lost the sound in two 

 minutes, and the Putnam nine minutes later. As each 

 steamer was moving from the other at the same rate, the 

 distance of the sound heard moving against the wind would 

 be represented by 4, while the distance of the sound moving 

 with the wind would be represented by 9 X 2 + 4=22, the 

 ratio being again 1 : 5|. 



Fifth experiment. — This experiment was made August 10, 

 by the same vessels and same observers: wind W. S. W., of 

 about the same intensity as on previous days; barometer 

 30-1 ins.; dry bulb 74° F., wet bulb 69°. The Putnam 

 steamed against the wind, and the Mistletoe in the opposite 

 direction. The Putnam lost the sound in two minutes, and 

 the Mistletoe nine minutes later. The two vessels moving 

 apart with equal velocity, the space traversed by the sound 

 moving against the wind was represented by 4, while that 

 in the opposite direction was represented by 22 viz., 9 X 

 2 + 4=22. 



Sixth experiment. — The vessels were next separated in a 

 direction at right angles to the wind, when each lost the 

 sound of the other on an average of six minutes, giving a 

 distance travelled by the sound (while audible) of 12 spaces. 



Seventh experiment. — The vessels were next directed along 

 an intermediate course between the direction of the wind 

 and a line at right angles to it with the following results: 

 The Mistletoe, against the wind, lost the sound in about two 

 minutes, while the Putnam heard the sound seven minutes 

 longer. As in the previous case, the two vessels moving 



