Science, The Fallacy of The Present Theory of Sound.

Waikato Times, Volume XXV, Issue 2030, 11 July 1885, Page 2 (Supplement)

Science, The Fallacy of The Present Theory of Sound.

from The Scientific American Supplement. Dn. H. A. Mott rooently delivered a lecture before the New York Academy of Sciences, in Columbia College, on the Fallacy of the Present Theory of Sound. He commenced his lecture by stating that " the object of science was not to find out what we like or what we dislike; the object of science wan truth." He thon said that, as Galileo stated a hypothesis should be judged by the weight of the facts and the force of mathematical deductions, he claimed the theory of sound should bo so examined, and not allowed to exist as a true theory simply because it is sustained by a long line of scientific names; as too many theories had been overthrown to warrant the acceptance of any one authority nnlesa they had been thoroughly tested. Dr. M" 4 i s.sted that Dr. Wilford T*dii was the first to attack theory 01 Bound and show its fallaciousness, and that many other scientists besides himself had agreed with Dr. Hall in his arguments and had advanced additional arguments and experiments to establish this faot. Dr. Mott first gave * very elaborate and Rtiil at the same time condensed statement of the current theory of sound as propounded by such men rb Helmhollz, Tyndall, Lord Eayleigh, Mayer, Rood, Sir Wm. Thomson, and others, and closed this seotion of the paper with the remarks made by Tyndall : " Assuredly no question of science over stood so much in need of revision aa this of the transmission of sound through tho atmosphere. Slowly but surely we mastered the question, and the farther -we advanoo, tho more plainly it appeared that our reputed knowledge regarding it was erroneous from beginning to end." Dr. Mott then took up the other side of thn queition, and treated tho eame under the following heads:— 1. Agitation of the air. 2. Mobility of tho atmospheie. 3. Resonance. 4 Heat and velocity of the supposed sound wavei. 5 Decrease in loudness of Bound. 0. The phy sical strength of the locust. 7. Tne baromo trie theory of Sir William Tnomson. 8 Elasticity and density of the air. 0 I1I 1 ter ferenco and beats. 10- Tha meaibrana timpani and the corti arches. Under tho first head Dr. Mott stated thut all experiments and photographs mide to establish the existence of sound waves siruplv referred to the necessary agitation of the air accompanying any disturbance, such aa would of neceailty be produced by a vibrating body and had nothing to do directly with sound Ha itated that in the Edison telephone, sound was converted directly into elec tricity without vibrating any diaphragm at all, as attested to by E iison hioisolf Speaking of the mobility of the air, he said the particles were free to slip around and not practically be pushed at all, and that the greatest distance a eteam whittle could effect the air would not exceed 30 feet, and the waves would not travel more than 4 or r> ftct a second, while sound travels 1,120 feet a second. Under heat and velocity of eound waves, Dr. Mott stated that Newton found by calculating the exact relative density and elasticity of air that sound should travel only QIC feet a second, while it was known to travel 1,120 feet a second. Laplace, by a heat and csld theory, tried to account for the 171 feet, and supposed that in tho condensed portion of a sound wave heat was generated, and in the rarefied portion cold was produoed, the heat augmenting the elasticity and therefore the sound wave?, and the cold produced neutralizing the heat, thus kept the atmosphere at a constant temperature. Dr. Mott stated that when Newton first pointed out this discrepancy of 171 feet, the theory should have been dropped at once, and later on be showed the oonseqaences of Laplace's heat and cold theory. The great argument of the evening, and the one to whioh he attached the most importance, was that all Ecienti&t* have spoken of the swift movement of the tuning fork, while in fact it moved 25,000 timeo Flower than the hour hand of a clock, and 300,000,000 timeß slower than any clock pendulum ever constructed. Since a pendulum cannot, according to the high authorities, prodaoe sonorous air waves on account of its slow movement. Dr. Mott asks some one to enlighten him how a prong Of a toning fork going 300,000,000 slower conld be able to prodace them. He then showed that there was not the slightest similarity between the theoretical Bound waves I and water waves, and still they are spoken of as "precisely similar" and "essentially identical," and " move in exactly the same way." Considerable merriment was occasioned when Dr. Mott showed what a locust stridulating in the air would be culled upon to do if the picsenfc theory of sound wero correct. He stated that a locnsfi not weighing more than half a pennyweight, and that could not move an ounce weight, was supposed capable of setting 4 cubic miles of atmosphere into vibration, weighing 120 000,000 tons, so that it would be displaced 110 times in one second, and any portion of the air oould bend the human tympanic membrane once in and once out 410 times in one seoond; and that 40,000,000 people, nearly the whole population of the United State?, could have their 5,000 pounds of tympanic membrane thus shaken by an insect that could not move an ounce weight to save its life; and that the 231,222 pounds of tympanio membrane of the entire population of the earth, amounting to 1,3.j0,000,000, Under the last head of his paper Dr. Mott proved that the membrana tympani was not necessary for good hearing, that in fact when it was punoturwd, a deaf man oould in many cases be made to hear, and in fact it im proved the hearing in general ; the only reason why the tympanio membrane was not pancturcd oftner was that dust, heat, and cold were apt to injure the middle ear. In dosing his paper Dr. Mott said that he would risk the fallacy of the current theory of sound on tho argument advanced relating to the impossibility of the slow motion of a tuning fork to produce sonoious waves, and stated that ho would retire if any one could show the fallacy of the argument; bat if not, the wave theory must be abandoned as absurd and fallacious, aa was the Ptolecuaio *ystfm of astronomy, which was handed down from age to age until Copernicus and his aide de camp Galileo g»7e to the world a better yitem.

who could conveniently stand in 11 [ aqmrn rnileq, would be affected the pame w»y by 31 loc i c ttj stridnlatinq in the mr. A"cor ii".j; to the barometric theory of Sir WVlnm Th" ••>- "in i^ sbow.d th&fca loat'twmH Ivive U. hM G'looo 000 pouncli to the wt-uht of tl^ atmosphere. Ui:ct r obitioity Rjid dpnsity li 1 ) r Ute<l tbn«- < li»ticity w.iß a mere property of ft bo 'y , at d coiilfl not »Jd one grain of f'trofi to th^t ex f-rci-ul by the locust, si a* to a^'i'H ii f > !«• performing snch wonderful feata. Undor in terference he showed that the lav/ cf inter ferpiico ia fallacious; tint no Buoh_ thirg occura ; and that in the experiment with tho <?iron to show euch fact, the octave is produced which of necessity ought to be when tho number of orifices arc alternately doubled, and the fame effrcfc would be produced with one disk with tho double number of holes.