RESEARCHES IN SOUND. 507 



ber of cases have been reported by otlier observers in which, under 

 peculiar conditions of the weather, this phenomenon has been observed. 



To briefly recapitulate the results, we have in this case three instances, 

 in succession, in which a sound was heard farther from the west than 

 from the east, although in the mean time the wuid had changed to nearly 

 an opposite direction. Had these results been deduced from the first 

 observations made on the hitluence of wind on sound, or, in other 

 words, without previous experience, the conclusion would have been 

 definitely reached that something else than wind afi'ected the convey- 

 ance of sound, and this conclusion would have been correct, if the sug- 

 gestion had been confined to the wind at the surface ; but from previous 

 observations and theoretical conclusions, the observed phenomena are 

 readily accounted for by supposing that during the whole time of ob- 

 servation the v.iud was blowing from the west in tlie higher part of the 

 aerial cm-rent, and that the calm and opposing wind observed were con- 

 fined to the region near the surface. To test this hypothesis. Major 

 Haius constructed a balloon of tissue-paper, which, after being com- 

 pleted, was unfortunately burned in the attempt to inflate it with heated 

 air. 



The remainder of this day was devoted to observations on the sound 

 of the siren at the bght-house at Sandy Uook. For this purpose the 

 Cactus, under Captain Davis, was directed to steam in the eye of the 

 wind, while the Mistletoe, under General Woodruff, steamed before the 

 wind, and the Putnam steamed at right angles to the wind. Unfor- 

 tunately, on account of the diminution of light at the closing in of the 

 day, nothing could be observed. The only result obtained was that one 

 of the duplicate sirens was heard more distinctly than the other, namely, 

 the one with the higher note. 



Experiments September 24, 1874. — The place chosen for the observa- 

 tions of this day was still farther out in the ocean, at the Sandy Hook 

 light- vessel, G miles from the nearest point of land. The pressure of the 

 atmosphere was a little greater than the day before, being 30.52 ; the 

 temperature about the same, 72° Fahr. wind light, from a westerly 

 direction, as on the previous day, with a force, as indicated by the 

 anemometer, of 1,2 miles per hour. Having been provided with a num- 

 ber of India-rubber toy balloons, the two vessels were sent off in opposite 

 directions — the Mistletoe toward the west, against the wind, the Cactus 

 toward the east, with the wind, leaving at 10:40 A. m. A change was 

 also made in observing the sound. In these observations the sound was 

 noted at each vessel from the other, the speed of the steamers being the 

 same,; the distance between them when the Mistletoe lost the sound of 

 the Cactus was two miles, while the Cactus continued to hear the ]\Iistle- 

 toe's sound coming with the wind until they were four miles apart. Simul- 

 taneously with this observation a balloon was let olf from the Putnam 

 at the light-vessel, which, in its ascent, moved continuously obUquely 



