614 



SCIENCE. 



front in a homogeneous medium is a spherical surface, and 

 the rays of sound proceed outwards in all directions and 

 in straight lines ; hence the nearer is the source of sound, 

 the more convex is the wave front and the more diverging 

 are the rays. When the nearly parallel rays of sound 

 proceeding from a distant point, strike the cup-shaped 

 outer ear, a part is reflected toward the centre and thus 

 reinforce the rays which directly enter the external open- 

 ing of the ear. If a sound proceed from a point very 

 near the ear the rays will be so diverging that all, except 

 such as directly enter the opening, will be reflected out- 

 wards and will be lost. Hence it is evident that a far 

 sound will seem louder than a near one, if their vibrations 

 are of equal intensity as they come to the outer ear. This 

 will at once upset the theory that loudness and intensity 

 vary according to the same laws, unless in some way 

 the far sound shall lose its advantage after entering the 

 external meatus; but, as they enter the tube, the diverg- 

 ing rays of the near sound will strike obliquely outwards 

 against the walls and will be reflected. Thus a part of 

 their energy will be lost, a much larger proportionate loss 

 than will come to the more parallel rays of the far sound. 

 When at length after various reflections from the walls 

 of the crooked meatus, the waves are wedged between 

 one wall and the membrane of the tympanum which is 

 placed obliquely across the inner end of the tube, the rays 

 will fall upon the concave outer surface of the membrane, 

 and a part will be converged. The more parallel rays of 

 the distant sound will be more converged than those of 

 the near sound, and hence will reinforce the impulse at the 

 center of the membrane more than the other ; but the 

 center is the point of greatest leverage against the ham- 

 mer bone which is fastened to the back of the membrane ; 

 hence nearly parallel rays of sound would more vio- 

 lently agitate the tympan of the inner ear than more di- 

 verging rays, even though both were of the same inten- 

 sity before striking the concave membrane of the tympa- 

 num. The comparison by the ear of the intensities of two 

 sounds would be still more untrustworthy if one of the 

 sources of sound were within the outer tube of the ear. 



Loudness, that is, the intensity of sound sensations, 

 does not, then, depend upon the energy of the external 

 sound vibrations, but upon the proportion of the energy 

 which the mechanism of the ear is able to transmit to the 

 auditory nerves, which amount is variable. The ear is so 

 made as to relatively strengthen distant sounds and to 

 weaken near ones, and it is so much the better an in- 

 strument because of this, for we are thereby saved from 

 too violent shocks of the nerves, which are most likely to 

 come from near sounds, while at the same time we retain 

 a wide range of hearing. Such illustrations as that of the 

 bells would not be chargeable with setting up a false test 

 for the verification of physical laws, if it was not at the 

 same time explained that the intensity of the sensation of 

 hearing does not, and in consequence of the peculiar con- 

 struction of the ear, cannot vary as the energy of the 

 moving particles of the sound wave ; also that at cer- 

 tain distances the testimony of the ear will approximately 

 coincide, at other distances it will not coincide with the 

 laws of intensity of sound which have been established 

 by mathematical reasoning. The errors involved in the 

 argument from the bells are very commonly held ; it is 

 not evident that all such arguments ought to be elimin- 

 ated from treatises on sound, or at least that their true 

 significance ought to be explained, and that the distinc- 

 tion should be more clearly defined between the subjec- 

 tive word loudness and objective word intensity. 



GEORGE H. STONE. 

 Colorado Springs, December is/., 1881. 



New York, Dec. 19///. 



To the Editor of "Science." 



In the official report of my paper read before the N. Y. 

 Academy ol Sciences, published in your last issue (Dec. 

 16th), I notice the cost of the balloon is given at about 



^12,000, whereas the amount should have been ^4,000. 



The report also states, " the great body of warm 

 water that flows northward by the peninsula of Norway 

 and Sweden strikes the lighter currents near the Pole 

 and goes on as a submarine current, sweeping around 

 the Pole till it goes out again through Smith's Sound." 

 I desire to say that it is obvious that only a part of the 

 current passes through Smith's Sound. 

 Respectfully, 



John P. Cheyne, R.N., F.R.G.S. 



To the Editor of " Science." 



Sir, — In No. 12 of this year's American Naturalist I 

 notice a short paragraph on 'fossil organisms in meteor- 

 ites.' The subject certainly is interesting and it seems 

 perfectly proper that the 'A. N.' should at last take notice 

 of it. 



The only objection that I may be allowed to raise on 

 behalf of " SCIENCE " and perhaps of myself is that the 

 American Naturalist did not duly give credit for what 

 had been reprinted from your columns.* I cannot con- 

 ceive any plausible reason — unless it be an oversight — 

 why this simple duty of editorial courtesy should be ne- 

 glected by an American contemporary, while every Eng- 

 lish scientific journal takes pains to give due credit to 

 " Science " for all the various data and notes which are 

 gleaned from its columns {e.g. Jour. Microsc. Soc, Lan- 

 cet, Crookes' Journal, Journal of Science.) 



As to the sceptical remarks with which the A. N.' s 

 paragraph concludes, to the effect that "a great deal 

 more evidence will be required by biologists before 

 crediting these alleged discoveries," I may refer all seep 

 tics to Mr. Darwin's opinion, as reported in No. 61 of 

 your valuable journal and to any (silicious) meteorite on 

 which they can lay their hands and grind transparent 

 sections from. This will go far to supply the wanted 

 evidence. 



Very respectfully, 



Geo. W. Rachel, M. D. 



To the Editor of " Science." 



Nashville, Tenn., Nov. 30, 181 1, 



Dear Sir, — I have to-day received from Mr. H. H. 

 Warner, of Rochester, N. Y., $200 (two hundred dollars), 

 the " Warner Comet Prize" for the discovery of Comet 

 E, 1881, on Sept. 17. 



Respectfully, 



E. E. Barnard. 



MUSICAL FENCES. 



In the abstract of an interesting paper by Prof. S. W. 

 Robinson, in a recent number of "Science," the au- 

 thor begins with the statement that " this sketch is mainly 

 of a simple fact of observation." He gives then a clear 

 exposition of the acoustic phenomena observed by him in 

 walking past picket fences, and the mathematical formula 

 expressing the law of retrogression ot pitch. 



The observation is by no means new. I am unable to say 

 at what time it was first published, if at all, but am sure 

 that it was made nearly as far back as twenty years ago. On 

 the crisp, cold morning of December 31st, 1861, while 

 taking a walk with Prof. Joseph Le Conte, myself being 

 innocent of mathematics on account of my youth, we 

 noticed the whistling sound returned by a picket fence 

 past which we were moving, our feet striking sharply 

 against the frozen earth. My fondness for music made 

 me particularly appreciative of a musical fence, and I 

 have noticed the phenomenon hundreds of times since 

 that date, knowing its explanation qualitatively, though I 

 did not deduce the formula. If the fence be long, and 

 the distance between the wickets considerable, the re- 

 turning whistle may be much longer in duration than a 

 quarter of a second. The stroke of a hammer on a board 



*S. my paper on the subject in Science No. 50. 



