Dr. H.A. Mott recently 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 was
truth." He then said that, as Galileo stated a hypothesis should be judged
by the weight of facts and the force of mathematical deductions, he
claimed the theory of sound should be 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 unless they had been thoroughly tested.
Dr. Mott stated that Dr. Wilford Hall was the first to attack the theory
of sound 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 fact. Dr. Mott
first gave a very elaborate and still at the same time condensed statement
of the current theory of sound as propounded by such men as Helmholtz,
Tyndall, Lord Rayleigh, Mayer, Rood, Sir Wm. Thomson, and others, and
closed this section of the paper with the remarks made by Tyndall:
"Assuredly no question of science ever stood so much in need of revision
as this of the transmission of sound through the atmosphere. Slowly but
surely we mastered the question, and the further we advance, the 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 the question, and treated the same
under the following heads:
1. Agitation of the air. 2. Mobility of the atmosphere. 3. Resonance. 4.
Heat and velocity of the supposed sound waves. 5. Decrease in loudness of
sound. 6. The physical strength of the locust. 7. The barometric theory of
Sir Wm. Thomson. 8. Elasticity and density of the air. 9. Interference and
beats. 10. The membrana tympani and the corti arches.
Under the first head Dr. Mott stated that all experiments and photographs
made to establish the existence of sound waves simply referred to the
necessary agitation of the air accompanying any disturbance, such as would
of necessity be produced by a vibrating body, and had nothing to do
directly with sound. He stated that in the Edison telephone, sound was
converted directly into electricity without vibrating any diaphragm at
all, as attested to by Edison himself. 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 steam whistle could affect
the air would not exceed 30 feet, and the waves would not travel more than
4 or 5 feet a second, while sound travels 1,120 feet a second. Under heat
and velocity of sound waves, Dr. Mott stated that Newton found by
calculating the exact relative density and elasticity of air that sound
should travel only 916 feet a second, while it was known to travel 1,120
feet a second.
Laplace, by a heat and cold theory, tried to account for the 174 feet, and
supposed that in the condensed portion of a sound wave heat was generated,
and in the rarefied portion cold was produced; the heat augmenting the
elasticity and therefore the sound waves, 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 174
feet, the theory should have been dropped at once, and later on he showed
the consequences of Laplace's heat and cold theory.
The great argument of the evening, and the one to which he attached the
most importance, was that all scientists have spoken of the swift movement
of the tuning fork, while in fact it moved 25,000 times slower than the
hour hand of a clock and 300,000,000 times slower than any clock pendulum
ever constructed.
Since a pendulum cannot, according to the high authorities, produce
sonorous air waves on account of its slow movement, Dr. Mott asks some one
to enlighten him how a prong of a tuning fork going 300,000,000 times
slower could be able to produce them. He then showed that there was not
the slightest similarity between the theoretical sound waves 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 called upon to do if the present theory of sound were
correct. He stated that a locust 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 440 times in one second,
and any portion of the air could bend the human tympanic membrane once in
and once out 440 times in one second; and that 40,000,000 people, nearly
the whole population of the United States, 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 tympanic membrane
of the entire population of the earth, amounting to 1,350,000,000, who
could conveniently stand in 11¼ square miles, would be affected the same
way by 34 locusts stridulating in the air. According to the barometric
theory of Sir William Thomson, he showed that a locust would have to add
60,000,000 pounds to the weight of the atmosphere.
Under elasticity and density he stated that elasticity was a mere property
of a body, and could not add one grain of force to that exercised by the
locust, so as to assist it in performing such wonderful feats. Under
interference he showed that the law of interference is fallacious; that no
such thing occurs; and that in the experiment with the siren to show such
fact, the octave is produced which of necessity ought to be when the
number of orifices are alternately doubled, and the same effect would be
produced with one disk with double the number of holes. 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 punctured, a deaf man
could in many cases be made to hear, and in fact it improved the hearing
in general; the only reason why the tympanic membrane was not punctured
oftener was that dust, heat, and cold were apt to injure the middle ear.
In closing his paper Dr. Mott said that he would risk the fallacy of the
current theory of sound on the argument advanced relating to the
impossibility of the slow motion of a tuning fork to produce sonorous
waves, and stated that he would retire if any one could show the fallacy
of the argument; but if not, the wave theory must be abandoned as absurd
and fallacious, as was the Ptolemaic system of astronomy, which was handed
down from age to age until Copernicus and his aide de camp Galileo gave to
the world a better system.
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