TV^. B. Taylor— Recent Researches in Sound. 101 



between opposit 

 of movement in each success! 

 it is wholly improbable that the sound-beam which reaches the 

 observers ear, ever passes high enough to approach the upper 

 " ideal wind," nothing is neutralized. Obedient to the law of 

 instantaneous resultants, the beam of acoustic impulse presses 

 on ever at right angles to the wave-surface which is conditioned 

 by compounded factors. 



"^ As wide of the mark is the supposition that the upper and 

 opposing " ideal wind " is " for the purpose of tilting again the 

 already lifted sound-wave, downward." As has been just con- 

 tended, the one wind is as incapable of depressing the sound- 

 wave, as the other is of lifting it. 



The misconception culminates in the objection that " Profes- 

 sor Henry does not explain how the sound-wave re-crosses the 

 hostile lower current, nor does he give any definite notion of 

 the conditions under which it can be shown that it will reach 

 the observer." (Loc, cit, p. 20.) There is no " hostile lower 

 current," since as above pointed out, an opposite wind may be 

 just as favorable to the propagation of sound, 



To give, however, a 



the observer without crossina: currents 

 crrams are submitted. 



,, the ac< 



3ompanying dia- 





1 i 



\ I j r 



MI7//JLL 



1 1^ 



W-^ 



Fig. 1 ex 

 in depressir _ 



o the point of observation ; the wind blowing from W. to A. 

 As the spheroidal wave-faces become more pressed forward 

 above by the freer wind (assuming it to be retarded at the sur- 

 face by friction), and as the direction of the acoustic beam is 

 constantly normal to the successive aerial surfaces of impact, it 

 follows that very minute differences of concenfricity in the suc- 

 cessive waves, will by constant accumulation gradually bend 

 the line of dynamic effect downward, as shown in the sketch on 

 a very exaggerated scale. Of the sound rays below the line 

 represented, some will by reflection from the sea, reach the ob- 

 server's ear and thus increase the sound. 



Fig. 2 represents the ordinary effect of an opposing wind here 

 blowing from E. to W. The wave faces being more resisted 



