of white paper, rendered adhesive by gum water. To this the blue particles adhere, and form these fantastic shapes; and the labor of days becomes the operation of a few minutes. The parts where an accumulation of sand takes place, are called nodal lines. When the plate vibrates, these are at rest, and the particles are heaped up from the places of agitation. The sounds called harmonics which a skilful player draws from the violin, are formed by placing the finger on some one of the nodal points of the vibrating string. A slip of paper, cut in the shape of a reversed V, and made to ride upon a musical cord in vibration, will find the nearest node and there sit at rest. The same is true of a rod or bar, and a plate may be regarded as composed of a quantity of parallel rods. The discs employed in these experiments should be perfectly homogeneous, and M. Savart has given the preference to brass, as the substance most susceptible of uniform density and polish. Plates of this metal are preferable to glass discs the latter being brittle. Various forms are employed, and certain laws and properties have been ascertained, with much patience and ingenuity. Whether the plate be square, or round, or oval, or triangular, the lines composing the figures have been found never to intersect. They bend, and assume in the circle, for instance, the appearance of radii, while in reality they are curved at the centre, which, like the asymptote, they approach but never touch. The experiments of Wheatstone and Chladni have been continued of late years, and the philosophical transactions are full of rich and varied specimens of these acoustical figures. Since certain principles have been discovered respecting their formation, are we to despair of seeing a symphony or concerto one day delineated in these magical outlines? A note or an accord revealed by every graceful curve in nature, were fresh sources of inspiration to the composer.

In this captivating science, each day reveals some new phenomenon, as beautiful as inexplicable, and its delighted yet puzzled votaries grope in the dark amongst innumerable sounds and vibrations. Is it not singular, in this age, a science, philosophically speaking, in its infancy? And stranger yet seems the infatuation of those who consecrate their lives to a branch of knowledge centuries may not be able to systematize. There must be in the pursuits of science a fascination superior to the intensest allurements of pleasure. The maddest disciple of Epicurus would forswear enjoyment, did its Hierophants exact one half the devotion the naturalist and the student voluntarily pay

to Minerva. We need cite no other instances than the cultus of the professor, whose discoveries we have sometimes alluded to, in the course of this article.

All Paris had patiently expected, for years, the course of lectures in which M. Savart proposed unfolding the acoustical phenomena and principles half his life had been consumed in investigating. The philosopher was not ready-some dissonances of sound or of experiment awaited a resolution, time and patience alone could develop. The public was patient. Its curiosity was finally gratified. The course announced for December, 1837, was opened in March, 1838. A numerous auditory greeted the experimenter. Many classes of society sat upon the same benches; M. Becquerel, the president of the academy of sciences, himself long an anchorite of science, beside the neophyte escaped from school to the Sorbonne- the journalist beside the blue stocking. The spacious amphitheatre was propitious for the illustration of the new revelations, and the area reserved for the lecturer, ample enough for the enactment of a modern drama. A variety of novel apparatus lay within his reach, and above the chimney-piece of the furnace, the following names of eminent natural philosophers, inscribed in golden characters upon marble tablets, were, surely, the happiest auspices under which a new series of physical inquiries could be insti

Besides its novelty and intrinsic interest, one chief merit of M. Savart's course, was the frank and lucid mode of explanation he adopted. Responding gladly to all interrogatories; free to acknowledge the difficulties which had baffled him, and narrating familiarly the history of each discovery, he seemed more like a brother worshipper from the crowd, than an interpreter of one of nature's thousand oracles. His lectures had but one defect; they were too few and the audience regretted the vaca

tion that brought them to a close. These few traits we have gathered from the lips of one on whom the perfect ease, and nature, and perseverance, and ingenuity of the intelligent professor made a lasting impression. M. Savart is the type of an experimentalist in the nineteenth century. What M. Becquerel has achieved for electricity, he has accomplished for acoustics. We could hardly award him a more simple, yet expressive, meed of praise.

His name occurs frequently in the third part of Mr. Peirce's treatise, which enumerates the various recent experiments made by him, and confirmed by Faraday, upon the communication of vibrations from one part of a system to another. Here, also, learn we, how the vibrations of a chord are strengthened by the violin it is stretched upon, and how those of one sonorous body are communicated by the air to another susceptible of the same mode of vibration. Thence we gather, through the skillful experiments of the French professor, some notion of the secrets employed in building the ancient amphitheatres, of the use of those rasa mentioned by Vitruvius, and of the flutes which sounded the proper pitch for the voice of the Roman orator.

We miss some not less curious facts of the same nature, due, also, to M. Savart, whose delicately organized ear is well adapted to these researches. He found that the sound of a string, or pipe, or any other instrument, exerts a very remarkable influence on thin streams of water escaping under a sufficient pressure through a small circular aperture. When the orifice is horizontal, and the stream flows perpendicularly, it will be found, upon issuing, to assume the figure of a cylinder somewhat conical-immediately below the apex the liquid column swells; an annular compression follows, then a new dilation, and so on successively. The fluid seems to assume this form of column in consequence of its vibrations; for, by a practised ear, it is perceived to emit a feeble sound, which may be confirmed by receiving the stream upon a stretched membrane. This ingenious apparatus is known to vibrate in unison with every sound communicated to it. Let us suppose that in the present case, it reveals A as the note produced by the vibrating fluid. Producing this note upon a violin or bass-viol- as the pitch may require -suddenly the water-stream is seen to obey the magical power of music, and to execute a kind of dance. On sheets of water the effect is still more remarkable. Columns allowed to fall upon conical and other surfaces form symmetrical sheets, or undulate like things of life, twining themselves with caprice, and

grace, and elasticity. By proper instruments the very cataract might be made to jump with unknown joy, and the rain to fall in rhythmic measure. After these beautiful experiments, who will deny that, as poets say, matter recognises harmony, and that, to verify the fable of Orpheus, we have only to multiply by centuries, and their vague superstitions, the interesting feats of Mr. Savart. But how wondrous soever such facts may appear, philosophers will ever seek, and sometimes succeed in accounting for them. For ourselves, we can but see in every effect an almighty cause, whose manifold, yet simple means, are each capable of originating a thousand varied phenomena which increase in mystery the nearer we approach the source from whence they flow.

By studying the manner in which sound is produced in the various musical instruments, we may attain a knowledge of the vocal mechanism by which we communicate our ideas, and of the apparatus through which we are impressed with those of our fellow creatures, by the melody of voice or of instrument. These subjects are respectively discussed in the two concluding chapters of the volume before us. We can hardly presume to descant upon these topics here, and only extend our remarks because the explanations of them afforded by Mr. Peirce appear less satisfactory than the preceding portions of his work. It is true, physiologists have failed to teach us the use of every part of that very complicated organ, the ear, but we may, nevertheless, partially divine how we receive impressions of articulate and musical sounds, two functions, for which different organs may evidently be requisite. It is our belief, that in the human ear these are combined; that the vestibulus is, with its adjacent parts, the seat of the one, and the partition which bisects the cochlea, that of the other.

The vestibulus is a small cavity, exhibiting windows closed by membranes, and filled with a gelatinous fluid highly susceptible of vibration. From the inner side, a nerve, forming a pencillike expansion in the liquid, connects this cavity with the brain. When the air is put in vibration by a sonorous body, the vibrations are communicated to the liquid, and thence to the numerous nervous threads which transmit them to the brain. Thus far all is indisputable. Beyond this, facts give place to hypotheses, and the mode in which the vibrations become articulate sounds-mingled as the question is with mysteries that seem impenetrable - will possibly never be revealed to man.

An anatomical examination of the partition in the cochlea,

NO. VII.-VOL. IV.

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shows it to be a lamina composed of innumerable chords, transverse to its length. Each of these is connected with a nervous thread, and the whole partition thus forms a kind of hearing harp. If we conceive that these miniature chords, by some reason unknown to us, may, notwithstanding their minuteness, each vibrate in unison with a musical note, exactly as is the case with musical strings, of the same fundamental tone, we have at once a key to our aptitude for hearing music. Thus, may we also comprehend why some persons, who distinguish the feeblest voice, have no taste for music, and why the same performance is known to produce opposite effects upon different persons. This is the opinion of an eminent physiologist, and seems worthy the attention of medical men.

By the foregoing theory, may be readily explained a curious fact, published in many of the public journals of the past year. A gentleman, in one of the most musical towns of Germany, displayed an aversion to music. If he chanced to be in a room where preparations for it were commencing, at the first sound of the piano or harp, he was constrained to withdraw. It was by accident remarked, that when one ear was stopped the other experienced all the pleasure harmony occasions. The supposition of a very slight difference in the musical apparatus of the two ears, as already described, will readily account for this singular circumstance.

In taking leave of Mr. Peirce, we would renew the expressions of our satisfaction with his treatise on acoustics. It is entitled the second volume of a course of natural philosophy, but its predecessor has not yet reached us, unless he refers to an excellent algebra, which we desire to recommend. It has been said that he is engaged in translating and preparing for the press, the concluding volume of the monument raised to the memory of Laplace, by the late Dr. Bowditch, and beneath which the grand and simple architect himself lies entombed. It is well known that Professor Peirce is the same intelligent young friend, who, in proportion as the sheets of the Mécanique Céleste appeared, read over and corrected them. Who, then, so well as he, can complete the interrupted task of his early benefactor?