96 W. B. Taylor— Recent Rese^o'ches in Sound. 



high), when set on a post 5 feet high, it could be heard 160 

 yards, or more than twice the distance, — the sound-beams 

 evidently rising faster at or near the ground, than they do 

 higher up. (p.' 69.) "The intensity of the sound invariably 

 seen] eel to waver, and as one approached the bell from the wind- 

 ward side, the sound did not intensify uniformly or gradually, 

 but by fits or jerks." This is supposed to be the result of the 

 more or less curved sound rays crossing each other at a small 

 angle and producing an ' interference." (p. 70.) 



A subsequent experiment was made on the 14th of March, 

 during a strong west wind, its velocity at an elevation of 12 

 feet being 87 feet per second, at 8 feet, 8B per second, and at 

 one foot from the ground (there being no snow on the grass) 17 

 feet per second. While the results as to varying range fully 

 coniirmed the previous experiments, the raismg of the bell 

 caused the sound to be heard even better against the wind than 

 in the direction of the wind. (p. 71.) This curious circum- 

 stance is explained by Professor Eeynolds as "due to the fact 

 that the variation in the velocity of the air is much greater near 

 the ground, than at a few feet above it;" and "when the bell is 

 raised the rays of sound which proceed horizontally will be 

 much less bent or turned up than those which go down to the 

 ground ; and consequently after proceeding some distance these 

 rays will meet or cross, and if the head be at this point they 

 will both fall on the ear together, causing a sound of double 

 intensity. It is this crossing of the rays also which for the 

 most part causes the interference " just mentioned, (p. 71.) 



Professor Eeynolds concludes that "these experiments es- 

 tablisii three things with regard to the transmission of sound : 

 1. That when there is no wind, sound proceeding over a rough 

 surface is more intense above than below. 2. That as long as 

 the velocity of the wind is greater above than below, sound is 

 lifted up to windward and is not destroyed. 3. That under the 

 same circumstances it is brought down to leeward, and hence 

 its range extended at the surface of the ground. These experi- 

 ments also show that there is less variation in the velocity oi 

 the wind over a smooth surface than over a rough one. It 

 seems to me that tiiese facts fully confirm the hypothesis pro- 

 pounded by Prof. Stokes; that they place the action of wind 

 beyond question ; and that they afford explanations of many of 

 the anomalous cases that have been observed." (p. 71.) 



nd, Professor Reynolds shows that a 

 perature between 32° and 70° adds approxii 

 second to the velocity of sound," there mus 

 upward flexure of the rays, whenever by rea 



