94 W. B. Taylor— Recent Researches in Sound. 



Art. VII. — On Recent Researches in Sound; by Wm. B. Taylor. 



[Continued from page 41.] 



IV. 



The communication of Professor Reynolds " On the Refrac- 

 tion of Sound by the Atmosphere," is in two parts; the first of 

 which considers " The effect of Wind upon Sound," and the 

 second part "The effect of variations of Temperature." The 

 experiments were all made in "a flat meadow of considerable 

 extent ;" and the apparatus employed " consisted of an electri- 

 cal bell mounted on a case containing a battery. The bell was 

 placed horizontally on the top of the case, so that it could be 

 heard equally well in all directions ; and when standing on the 

 ground, the bell was one foot above the surface." An anemome- 

 ter was also used to determine the velocity of the wind. (Pro- 

 ceedings of the Royal Society ; republished in the L. E. D. 

 Phil. Mag., for July, 1875, vol. 1, p. 67.) 



The experiments were made on four different days, the 6th, 

 9th, 10th, and 11th of March, 1874 ; and on the last two days 

 the ground was covered with snow, which furnished an oppor- 

 tunity of comparing the effect of diiferent surfaces on the range 

 of Sound. Additional experiments were made on the 14th of 

 March. 



[1.] '' On all occasions the effect of wind seems to be rather 

 against distance than against distinctness. Sounds heard to 

 windward [that is against the wind] are for the most part heard 

 with their full distinctness; and there is only a comparatively 

 small margin between that point at which the sound is percep- 

 tibly diminished, and that at which it ceases to be audible." 

 (Phil. Mag., p. 63.) 



[2.] The sound of the alarm-bell was always heard " farther 

 with the wind than at right-angles to its direction ; [contrary to 

 the old observation of De La Roche in 1816, — which was 

 obviously an exceptional one ;] and when the wind was at all 

 strong, the range with the wind was more than double that at 

 right angles WUh the wind, over the grass the sound 



could be heard 140 yards, and over the snow 360 yards, 

 with the head lifted or on the ground ; whereas at right-angies 

 to the wind, on all occasions the range was extended by raising 

 either the observer or the bell." (p. 68.) 



[3.] When the wind was light the sound beyond the distance 

 of 20 yards, was much less audible at the ground than a few feet 

 above it ; and when inaudible in every direction at standing 

 height, the sound could be distinctly recovered by mounting a 

 tree. The same result was obtained by raising the alarm-bell 



