SOUND-SIGNALS AT SEA, 87 



the mother can be found. The child can not determine its moth- 

 er's location by the sound of her voice. This exaggerated in- 

 stance may be owing to the reflection of the sound, not only from 

 the walls, but from the strata of air differing in temperature and 

 humidity. 



How many of us going to the next street, running at right 

 angles to the car-tracks, can tell, from hearing the bell of the 

 approaching street-car before the car comes in sight, whether 

 that car is going north or south ? It does not seem that animals 

 can determine the direction of sound much better than man. 

 The sleeping dog, roused by his master's call, is all abroad as to 

 his master's location, and determines it by sight or scent, or 

 both, frequently running in several different directions before 

 hitting the right one. The deer, on being startled by the un- 

 seen hunter's tread, is not always right in his selection of the 

 route to get out of harm's way. A flock of geese, ducks, or other 

 birds, on hearing a gun, is as likely to fly toward as from the 

 sportsman, if he has kept entirely out of sight, and the flash of 

 his piece has not been seen. 



It is a question whether the blind are better able to deter- 

 mine the direction of sound by ear than are seeing people. It is 

 possible that their senses of touch and smell are so highly devel- 

 oped that their instantaneous action with that of the ear give 

 them a decided advantage over seeing people in this matter. I 

 have known a blind man to be so sensible of the current of air 

 put in motion by the speaking of a single word in a room, that 

 he could select the speaker by his location, though others were 

 present. So, too, I have known a blind man to locate and iden- 

 tify the various people in the room, he saying he did it by the 

 different scent evolved from each, the seeing people there not 

 being sensible of any scent from any one. And yet he, when 

 standing in the middle of the room with his nose stopped, could 

 not give the direction of one single speaking person. 



Prof. Alexander Graham Bell reports, in a paper he read be- 

 fore the American Association for the Advancement of Science 

 at Saratoga in 1879, a series of experiments in binaural audition, 

 showing, among other things, that direction can not be appre- 

 ciated by monaural observation ; that when the source of sound 

 is at the nadir of the observer, the perception of its direction is 

 absolutely unreliable, and that not one of the many on whom he 

 tried the experiment had the slightest idea of the true direction 

 of a sound produced beneath him. 



"We are so much accustomed to the aid of our other senses, 

 especially that of sight, that we incline to give more value to 

 audition in determining direction than it deserves. That is one 

 reason why we err so largely when so placed that the eye can 



