EESEARCHES IN SOUND. ^ 525 



the distance travelled by tlie sound heard moving against the wind is 

 represented hy 4, while the distance of the sound heard with the wind 

 is rej^resented by 2(3 + 2=28, the ratio being 1:7. It should be men- 

 tioned, however, that the notes in this experiment are defective and 

 somewhat discrepant. 



Third experiment. — The Putnam went against the wind, the Mistletoe 

 in the opposite direction. The Putnam lost the sound of the whistle of 

 the Mistletoe in two minutes, while the Mistletoe continued to hear the 

 whistle of the Putnam ten minutes longer. Owing to a misunderstand- 

 ing, one of the steamers stopped for two minutes and then resumed its 

 course. As both steamers were separating dimng the first two minutes 

 with equal speed, the distance of the sound heard moving against the 

 wind is represented by 4, while the sound heard with the wind through 

 a space denoted by 2 x 10 -f 4—2=22, the ratio being 1 : bh 



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 uiinutes, 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 rep- 

 resented by 4, while the distance of the sound moving with the wind 

 would be represented by 9X2 + 4=22, the ratio bemg again 1 : oh. 



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° P. wet bulb, 09°. 

 The Putnam steamed against the Avind, and the Mistletoe in the opposite 

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

 toe nine minutes later. The two vessels moving apart with equal veloc- 

 ity, the si)ace traversed by the sound moving against the wind was rep- 

 resented by 4, while that in the opposite direction was represented by 

 22, viz, 9x2 + 4=22. 



Sixth experiment. — The vessels were next separated in a direction at 

 right angles to the wind, when each reciprocally lost the sound of the 

 other on an average of six minutes, giving a distance travelled by the 

 sound, while audible, of twelve spaces. 



Seventh experiment. — The vessels were next directed along an interme- 

 diate 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 

 apart with equal velocity would in two minutes be separated bj- a space 

 represented by 4, which would indicate the audibility of the sound mov- 

 ing against the wind, and for the same reason the other vessel, li earing 

 the sound seven minutes longer, would have the additional space repre- 

 sented by 14, and adding to this four spaces, we have 18 to represent 

 the audibility of the sound in the direction api)roximating that of the 

 wind. 



