led philosophers to the invention of this all-pervading luminiferous ether, extending, as is supposed, to the very outmost limits of telescopic vision, if not throughout all space. When Professor Young first suggested such a substance as ether, whose undulations might explain certain phenomena resembling those of sound, which no one had ever suspected to be other than caused by air-waves, it did not occur to this learned investigator that air-waves themselves, as the means of sound-propagation, were a pure fallacy of science, without one fact, or, when fully analyzed, appearance of fact, to warrant them, as will fully appear in due time. I am well aware that an intimation like this, after so many learned treatises on sound as the result of wave-motion have appeared from pens like those of Helmholtz and Tyndall, will naturally awaken in the scientific mind a feeling of contempt for its author, mingled perhaps with commiseration. Even my most intimate friends have warned me to desist from publishing these chapters, unless I wish to make myself ridiculous in the eyes of the scientific world, and be set down as a first-class candidate for a lunatic asylum. But as I have counted the cost and am not at all convinced of my insanity, I have, of course, declined the advice so gratuitously tendered. Before introducing a single argument against the hypothesis that sound is propagated by means of atmospheric undulations or any other kind of wave-motion, I wish to clearly state the difference between the old and the new hypothesis of Sound-propagation, and to name some of the well-recognized facts of these phenomena, on which there can be no controversy or difference of opinion, as the basis of all future argument. I do not propose to tear down the wave-theory without framing an hypothesis to take its place, and one which will serve as a basis for the solution of the undeniable problems presented in sound-phenomena. While maintaining, as I do, that the wave-theory is a most transparent and unmitigated scientific fallacy, I as strongly insist that, such fact being clearly established, there is nothing else left for sound to be but substantial emissions. It does not seem to me that a reflecting mind can draw any other conclusion than corpuscular emanations of some kind of substance, however attenuated it may be, if first of all the wavetheory breaks down hopelessly, as I shall attempt to show it must. Even if the substance constituting these sonorous pulses were conceded to be as attenuated as the material atoms composing Professor Tyndall's gelatinous luminiferous ether which forms the basis of lightwaves, I should still maintain that such substantial emanations are every way reasonable and consistent with Nature's analogues, many of which I will take occasion to introduce as the argument advances, while no advocate of the undulatory theory of light, and of these substantial waves of ether moving freely among the molecules. of the diamond, can reasonably object to substantial discharges of sound, when, as I have just had occasion to intimate light itself could just as well be supposed to radiate in the form of substantial waves or pulses, as first to ignore such a substance entirely, and then substitute another material (luminiferous ether) almost infinitely more difficult to accept.* *To account for the enormous velocity of propagation in the case of light, the substance which transmits it is assumed to be of both extreme elasticity and extreme tenuity. This substance is called the Luminiferous Ether. It fills all space; it surrounds the atoms of bodies. . . . The molecules of luminous bodies are in a state of vibration. The vibrations I admit at once, in thus assuming what must now be unavoidable in my hypothesis, namely, that the chirping of a cricket fills the surrounding air with substantial emanations,—that I invite, at first sight, the incredulity if not the ridicule of all scientific thinkers; but while this hypothesis will be shown to be entirely consistent with other well-known natural phenomena all around us, which no well-informed mind can doubt, it will be demonstrated that, according to the universally accepted wave-theory, the cricket is actually made to perform a miracle of physical power compared to which the crushing of a granite rock to powder by the drifting against it of a thistle-pappus would be as nothing. So, also, stands the question as regards sound. If atmospheric wave-motion is ruled out by fair logic and incontrovertible facts, there is no middle ground which can be assumed between it and substantial emissions. Professor Helmholtz lays down the principle in logic and science that a proposition is fairly sustained by the exclusion of all other supposable as sumptions. I shall therefore avail myself of this logic (since something must cause the sensation we term sound), and insist that if I shall clearly succeed in demonstrating the fallacy of wave-motion as the cause of sonorous sensations, then the corpuscular theory becomes necessarily established till such time as physicists shall discover and elucidate some more plausible middle ground as a solution of sound phenomena. I doubt not the scientific reader will readily admit the fairness and logica necessity of the position here assumed. What, then, is the real difference between the two hypotheses, one or the other of which must be accepted? Sound is undoubtedly generated by the I may also add, in this connection, that it never was thought of being urged in the arguments with Sir Isaac Newton, who strongly held to the corpuscular theory of light, that there was any possible middle ground between that view and the undulatory hypothesis; but rather it was tacitly conceded that if one was disproved the other was clearly substantiated. It was never intimated by any opponent of New-vibratory motion of whatever instrument ton's hypothesis-not even by the great mathematician Laplace-that if etherwaves were absolutely shown to be fallacious and impossible, some other hypothesis might be suggested besides substantial emanations. It seemed to be conceded on all hands that if wave-motion fell to the ground, the fact became established that light as substance of some kind must be taken for granted. are taken up by the ether and transmitted through it in waves," &c. "In fact, the mechanical properties of the ether are rather those of a solid than of an air."—"The luminiferous ether has definite mechanical properties. It is almost infinitely more attenuated than any known gas, but its properties are those of a solid rather than those of a gas. It resembles jelly ather than air."-TYNDALL on "Light," pp. 57,60. produces it, just as light is admitted to have its origin in the tremulous motion of the incandescent molecules of luminous bodies. Sound thus produced is claimed in this hypothesis to be a finely attenuated substance, which is radiated from the sound-producing body by an unknown law of diffusion, just as the radiant atoms of light, heat, magnetism, electricity, and even odor, are sent off from their respective sources. Science, as yet, has given us no light on the subject of radiation or conduction. It even can not explain osmotic action, or why liquids of different densities tend to mix or project their particles through each other, in opposition to the law of gravity; or why grains of odor tend to shoot through still atmosphere at considerable velocity, much less by what law magnetic atoms dart f from the poles of a magnet in ceaseless streams, or what motile force sends electric fluid through a wire at almost inconceivable velocity. It is enough for us, in the present investigation, to know that such laws of radiation and conduction do exist, and that each of these incorporeal substances named, if they be substances, such as Light, Heat, Magnetism, Electricity, Gravitation, Odor, and Sound, has its own peculiar law of radiation and conduction, suited by the Allwise Lawgiver to the use which each of these imponderable substances is intended to serve. As sound is generated by the vibratory action of the instrument which produces it, and consists (as I assume) of atomic emissions, it is in strict accordance with philosophy and reason that these corpuscular emissions should be radiated in sonorous pulses or discharges, instead of continuous streams, each discharge synchronizing with the vibratory movement of the string or other instrument which generates it, exactly as I have assumed light to be emitted from stellar bodies. The distance between these discharges as they pass off, or the interval occurring between their transmissions, determines the pitch of the sound. If the vibratory oscillations of the instrument be slow, thereby causing a low pitch, then the synchronous discharges of the sonorous substance will strike the tympanic membrane of the distant listener exactly the same intervals apart, and consequently will produce the same pitch of tone there. But if the sound-producing instrument vibrates rapidly, the sonorous discharges must necessarily pass off with a corresponding rapidity, and reach the ear with a correspondingly higher pitch of tone. Such discharges radiate through the atmosphere at ordinary temperature-say sixty degrees Fahrenheit at 1120 feet a second, as proved by careful observation. If sound consists of substantial atoms, as I propose to show must be the case before I conclude this treatise, then it must travel through whatever body conducts it let that be air, water, wood, or iron,in the manner here described, namely, as sonorous pulses or discharges, such discharges and vibrations keeping up their perfect synchronism or periodicity. The current theory of sound, in speaking of these sonorous discharges, calls them "air-waves," and the intervals occurring between them "wave-lengths," which determine, in the same manner as I have described, the pitch of tone. If the vibratory motions of the instrument be slow, the air-waves supposed to be "moulded" and sent off by such vibrations are said to be long, or to be of a considerable distance from crest to crest or from sinus to sinus, or, to use the technical phrase, "from condensation to condensation, and from rarefaction to rarefaction," as expressed by all writers on the subject. If the vibrations of the string or other soundproducing body be rapid, the waves will be short and the pitch of the sound correspondingly high. The undulatory theory teaches that these air-waves are moulded by the string or tuning-fork into "condensations and rarefactions," and sent off in this form to the ear, however distant so the tone is audible, producing the sensation of sound by the successive dashing of these air-waves against the tympanic membrane, thus causing the drum-skin of the ear to oscillate synchronously to such waves. Hence, that these air-waves, moulded and sent off by the vibrating string or fork, must travel undistorted the entire distance the sound is heard, it matters not what counteracting currents, waves, sounds, or atmospheric disturbances may cross their path! Perhaps there is no better place than right here to make a few brief citations from the highest living authorities on this subject, in order that the real position of scientists on the current wave-theory may not be misunderstood. These citations are selected because they concisely embody the popular notions regarding soundwaves, with an authority which is looked up to as standard in all our institutions of learning. I request the reader to carefully read them; and, if not familiar with this branch of scientific investigation, to study them, as a proper comprehension of their teaching will save time in prosecuting the argument, and prevent the necessity for frequently recurring to this list of passages. All my quotations from Professor Tyndall's Lectures on Sound, in the course of this argument, will be made from the second edition, except in a few instances from the third edition, which will be indicated. This occurs for the reason that most of the arguments were prepared before the third edition of Lectures on Souna was published. Professor Tyndall remarks as follows: 1.-" With regard to the point now under consideration, you will, I trust, endeavor to form a definite image of a wave of sound. You ought to see mentally the air-particles when urged outwards by the explosion of our balloon crowding closely together; but immediately behind this condensation you ought to see the particles separated more widely apart. You ought, in short, to be able to seize the conception that a sonorous wave consists of two portions, in the one of which the air is more dense and in the other of which it is less dense than usual. A condensation and a rarefaction, then, are the two constituents of a wave of sound." 2.- Fix your attention upon a particle of air as the sound-wave passes over it; it is urged from its position of rest towards a neighbor particle, first with an accelerated motion and then with a retarded The dis tance through which the air-particle moves to and particle, and causes it to recoil. fro, when the sound-wave passes it, is called the amplitude of the vibration. The intensity [loudness] of the sound is also proportional to the square of the amplitude." 3." The motion of the sonorous wave must not be confounded with the motion of the particles which at any moment form the wave. During the passage of the wave every particle concerned in its transmission makes only a small excursion to and fro. The length of this excursion is called the amplitude of the vibration.' 4.-"A sonorous wave consists of two parts, in one of which the air is condensed, and in the other of which rarefied. . . . In the condensed portion of a sonorous wave the air is above, in the rarefied portion it is below the average temperature. This change of temperature produced by the passage of the sonorous wave itself virtually augments the elasticity of the air, and makes the velocity of sound about one sixth greater than it would be if there were no change of temperature. . . . When I speak of a sonorous wave I mean a condensation and its associated rarefaction. . . . When a body capable of emitting a musical sound-a tuning-fork, for example-vibrates, it moulds the surrounding air into sonorous waves, each of which consists of a condensation and a rarefaction." 5. "We have already learned that what is loudness in our sensations is outside of us nothing more than width of swing or amplitude of the vibrating air-particles." 6.-"Having determined the rapidity of vibra tion, the length of the corresponding sonorous wave is found with the utmost facility. Imagine this tuning-fork vibrating in free air [384 vibrations to the second]. At the end of a second from the time it commenced its vibrations, the foremost ware would have reached a distance of 1090 feet in air at the freezing temperature. In the air of this room, which has a temperature of about 15° Cen., it would reach a distance of 1120 feet in a second. In this distance, therefore, are embraced 384 sonorous waves. Dividing, therefore, 1120 by 384, we find the length of each wave to be nearly 3 feet." 7.-"How are we to picture to ourselves the condition of the air through which this musical sound is passing? Imagine one of the prongs of the vibrating fork swiftly advancing; it compresses the air immediately in front of it, and when it retreats it leaves a partial vacuum behind, the process being repeated by every subsequent advance and retreat. The whole function of the tuning-fork is to carve the air into these condensations and rare- 8.-" Figure clearly to your minds a harp-string I also quote from Professor Helmholtz: 10.—“ Suppose a stone to be thrown into a piece of calm water. Round the spot struck there forms a little ring of wave, which, advancing equally in all directions, expands to a constantly increasing circle. Corresponding to this ring of waves sound also proceeds in the air from the excited point, and advances in all directions as far as the limits of the mass of air extend. The process in the air is essentially identical with that on the surface of the water." HELMHOLTZ, Sensations of Tone, p. 14. I have numbered the foregoing citations in view of possible reference to them as the argument advances. With these passages before the reader there need be no difficulty in grasping the essential features of the wave-theory of sound, which, in fact, up to the present moment, is the only hypothesis ever advanced, so far as I have been able to learn, by which to explain these well-known.phenomena. Other passages will be quoted, from time to time, as special questions come up for discussion. Believing, as I do, that the new hypothesis of sonorous discharges of some sort of attenuated substance will fully and satisfactorily explain all phenomena observed in sound, even better than they can be explained by physical and mechanical airwaves, I will at once make a practical application of the corpuscular theory to a few problems which have been always looked upon as conclusive proof of the air-wave hypothesis. The first and one of the most prominent examples of this kind is that of sympathetic vibration, or the surprising fact that if two strings or forks are tuned to perfect unison or in such a way that they will make exactly the same number of normal oscillations in a second, and if one of them is thrown into vibration, its unison neighbor if placed near enough to it will also start into vibratory motion, and sound audibly without any connection whatever with the actuating string or fork except the intervening air. The reason assigned for this by the advocates of the current theory, is, that the air-waves moulded and sent off from the excited string or fork, striking against its unison neighbor in synchronism with its own normal tendency to swing, start it gradually into oscillation, very feebly at first, but each succeeding air-wave dashing against it in perfect periodicity to its own vibrations, gives it a new impetus at every blow, till finally this sympathetic motion is brought to its maximum. This phenomenon, first observed by Pythagoras |