EESEARCHES IN SOUND. 469 



order of penetrating power was as follows: 1, trumpet; 2, exlianst; 3, 

 bell; these instruments being heard respectively at 5J, 3i, and 2 miles. 

 The whistle was not sounded. 



The second day simultaneous observations were made from two ves- 

 sels sailing- nearly in opposite directions. The results of the observations 

 made on the vessel sailing in a southerly direction were very irregular. 

 The trumpet was heard at 3g miles and lost at 4| miles with the wind 

 slightly in favor of the sound, and heard at C^ miles with the wind some- 

 what against the sound; it was heard even at 7| miles from the mast- 

 head, though inaudible from the deck. In all these cases the position 

 of the vessel was nearly in line with the axis of the trumpet. 



The whistle and exhaust were heard at 7^ miles with a feeble oppos- 

 ing wind, and lost at C^ miles when the force of the wind became greater. 



The order of penetration in this series of observations was : 1, trumpet 

 and gong; 2, whistle; 3, exhaust. 



In the case of the vessel sailing northward, its course being almost 

 directly against the wind and in the rear of the trumj^et, all the sounds 

 were lost at less distances than in the case of the other vessel. The 

 observations showed very clearly the effect of the wind, the bell at a 

 certain distance being heard indistinctly with a strong opposing wintl 

 and more and more plainly as the wind died away. The trumpet was 

 heard only as far as the whistle, the vessel being in the rear of It. 



The third day observations were made from the two vessels, both 

 however sailing to the south. From the vessel sailing at right angles 

 to the direction of the wind the order of penetration was : 1, trumpet ; 

 2, whistle; 3, exhaust; 4, bell. 



In the case of the other vessel the opposing effect of the wind was 

 greater, and the sounds were heard to a less distance; the order was: 

 1, trumpet; 2, whistle; 3, exhaust; 4, bell; 5, rocker. 



On the fourth day two tiips were made by the same vessel in the 

 course of the day, one being northward and the other southward. In 

 the first case the trumpet was lost at 3J miles, the vessel being nearly 

 in its rear; in the second case, the wind being almost directly opposed 

 to the sound, the large bell was heard at 1^ miles, and lost at |^ of a 

 mile, probably due to increase of the force of the wind ; the trumi^et was 

 was lost at 3i miles. 



In all these observations, owing to the unfavorable conditions of the 

 locality, and the direction of the wind, we were unable to obtain any 

 satisfactory' observations on sound moving with the wind. In all cases 

 the results were obtained from sounds moving nearly against the wind, 

 or at right angles to it. From the results of the whole it aj^pears that 

 the sound was heard farther with a light opposing wind than with a 

 stronger one, and that it was heard farthest of all at right angles to the 

 wind. From this latter fact, however, it should not be inferred that in 

 this case sound could be heard farther at right angles to the wind than 

 with the wind, but that in this direction the effect of the wind was neu- 



