1874] WRITINGS OF JOSEPH HENRY. 387 



from two vessels sailing in nearly opposite directions. The 

 results of the observations made on the vessel sailing in a 

 southerly direction were very irregular. The trumpet was 

 heard at 3f miles and lost at 4f miles with the wind slightly 

 in favor of the sound, and heard at 6^ miles with the wind 

 somewhat against the sound ; it was heard even at 7| miles 

 from the masthead, 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 opposing wind, and lost at 6i miles when the force of 

 the wind became greater. 



The order of penetration in this series of observations was: 

 1st, trumpet and gong ; 2nd, whistle ; 3d. exhaust. 



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

 almost directly against the wind and in the rear of the 

 trumpet, 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 wind 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. 



On 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 : 1st, trumpet; 2nd, whistle; 3d, exhaust; 

 4th, bell. 



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

 wind was greater, and the sounds were heard to a less dis- 

 tance; the order was: 1st, trumpet ; 2nd, whistle; 3d, ex- 

 haust ; 4th, bell; 5th, rocker. 



On the fourth day, two trips 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 3^ 

 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> 



