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Many experiments are mentioned by Kircher and others on the communication of sound through solid bodies, such as masts, yards, and other long beams of dry fir, with similar results. Dr. Monro has published a particular account of very curious experiments on the propagation of sound through water, in his Dissertation on the Physiology of Fishes; so that it now appears that air is by no means the only vehicle of sound. In 1760 Cotunni published his important discovery that the labyrinth or inmost cavity of the ear in animals is completely filled with water. This, after some contest, has been completely demonstrated (see Meckle Junior de Labyrinthi Auris Contentis, Argentor, 1777), and it seems now to be admitted by all. This being the case, our notions of the immediate cause of sound must undergo a great revolution, and a new research must be made into the way in which the nerve is affected; for it is not enough that we substitute the undulations of water for those of air in the labyrinth. The well informed mechanician will see at once, that the vivacity of the agitations of the nerve will be greatly increased by this substitution; for if water be perfectly elastic, through the whole extent of the undulatory agitation which it receives, its effect will be greater in proportion to its specific gravity and this is confirmed by an experiment very easily made. Immerse a table bell in water contained in a large thin glass vessel. Strike it with a hammer. The sound will be heard as if the bell had been immediately struck on the sides of the vessel. The filling of the labyrinth of the ear with water is therefore an additional mark of the wisdom of the Great Artist. But this is not enough for informing us concerning the ultimate mechanical event in the process of hearing. The manner in which the nerve is exposed to these undulations must be totally different from what was formerly imagined. The filaments and membranes which have been described by former anatomists must have been found by them in a state quite unlike to their situation and condition in the living animal. Accordingly the most eminent anatomists of Europe seem at present in great uncertainty as to the state of the nerve, and are keenly occupied in observations to this purpose. The descriptions given by Monro, Scarpa, Camper, Comparetti, and others, are full of most curious discoveries, which make almost a total change in our notions of this subject, and will, we hope, be productive of most valuable information. Scarpa has discovered that the solid cavity called the labyrinth, contains a threefold expansion of the auditory nerve. One part of it, the cochlea, contains it in a fibrillous state, ramified in a most symmetrical manner through the whole of the zona molis of the lamina spiralis, where it anastomoses with another production of it diffused over the general lining of that cavity. Another department of the nerve, also in a fibrous state, is spread over the external surface of a membranaceous bag, which nearly fills that part of the vestibule into which the semicircular canals open, and also that orifice which receives the impressions of the stapes. This bag sends off tubular membranaceous ducts, which, in like

manner, nearly fill these semicircular canals. A third department of the nerve is spread over the external surface of another membranaceous bag, which lies between the one just now mentioned and the cochlea, but, having no communication with either, almost completely filling the remainder of the vestibule. Thus the vestibule and canals seem only a case for protecting this sensitive membranaceous vessel, which is almost but not altogether in contact with the osseous case, being separated by a delicate and almost fluid cellular substance. The fibrillous expansion of the nerve is not indiscriminately diffused over the surface of these sacculi, but evidently directed to certain foci, where the fibres are constipated. And this is the last appearance of the fibrous state of the nerve; for, when the inside of these sacculi is inspected, no fibres appear, but a pulp (judged to be nervous from its similarity to other pulpy productions of the brain) adhering to the membranaceous coat, and not separable from it by gently washing it. It is more abundant, that is of greater thickness, opposite to the external fibrous foci. No organical structure could be discovered in this pulp, but it probably is organised; for, besides this adhering pulp, the water in the sacculi was observed to be clammy or mucous; so that in all probability the vascular or fibrous state of the nerve is succeeded by an uninterrupted production (perhaps columnar like basalt, though not cohering); and this at last ends in simple dissemination, symmetrical, however, where water and nerve are alternate in every direction. To these observations of Scarpa, Comparetti adds the curious circumstances of another and regular tympanum in the foramen rotundum, the cylindric cavity of which is enclosed at both ends by a fine membrane. The membrane which separates it from the cochlea appears to be in a state of variable tension, being drawn up to an umbo by a cartilaginous speck in its middle, which he thinks adheres to the lamina spiralis, and thus serves to strain the drumhead as the malleus strains the great membrane known to all. These are most important observations, and must greatly excite the curiosity of a truly philosophical mind, and deserve the most careful enquiry into their justness. If these are accurate descriptions of the organ, they seem to conduct us farther into the secrets of nature than any thing yet known. They promise to give us the greatest step yet made in physiology, viz. to show us the last mechanical fact which occurs in the long train interposed between the external body and the incitement of our sensitive system. But there are, as yet, great and essential differences in the description given by those celebrated naturalists. There seems to be no abatement of ardor in the researches of the physiologists; and they will not remain long ignorant of the truth or mistake in the accounts given by Scarpa and Comparetti.

To illustrate the cause of sound, it may be observed, 1st, That a motion is necessary in the sonorous body for the production of sound. 2dly, That this motion exists first in the small and insensible parts of the sonorous bodies, and is excited in them by the mutual collision against

each other, which produces the tremulous motion so observable in bodies that have a clear sound, as bells, musical chords, &c. 3dly, That this motion is communicated to, or produces a like motion in the air, or such parts of it as are fit to receive and propagate it. Lastly, That this motion must be communicated to those parts that are the proper and immediate instruments of hearing. Now that motion of a sonorous body which is the immediate cause of sound may be owing to two different causes; either the percussion between it and other hard bodies, as in drums, bells, chords, &c.; or the beating and dashing of the sonorous body and the air immediately against each other, as in flutes, trumpets, &c. But in both these cases the motion, which is the consequence of the mutual action, as well as the immediate cause of the sonorous motion which the air conveys to the ear, is supposed to be an invisible, tremulous, or undulating motion in the small and insensible parts of the body. Perrault adds that the visible motion of the grosser parts contributes no otherwise to sound than as it causes the invisible motion of the smaller parts, which he calls particles, to distinguish them from the sensible ones, which he calls parts, and from the smallest of all, which are called corpuscles.

The sonorous body having made its impression on the contiguous air, that impression is propagated from one particle to another, according to the laws of pneumatics. A few particles, for instance, driven from the surface of the body, push or press their adjacent particles into a less space; and the medium, as it is thus rarefied in one place, becomes condensed in the other; but the air thus compressed in the second place is, by its elasticity, returned back again, both to its former place and its former state; and the air contiguous to that is compressed; and the like obtains when the air less compressed, expanding itself, a new compression is generated. Therefore from each agitation of the air there arises a motion in it analogous to the motion of a wave on the surface of the water; which is called a wave or undulation of air. In each wave the particles go and return back again through very short equal spaces; the motion of each particle being analogous to the motion of a vibrating pendulum while it performs two oscillations; and most of the laws of the pendulum, with very little alteration, being applicable to the former.

Sounds are as various as are the means that concur in producing them. The chief varieties result from the figure, constitution, quantity, &c., of the sonorous body; the manner of percussion, with the velocity, &c., of the consequent vibration; the state and constitution of the medium; the disposition, distance, &c., of the organ; the obstacles between the organ and the sonorous object and the adjacent bodies. The most notable distinction of sounds, arising from the various degrees and combinations of the conditions above-mentioned, are into loud and low (or strong and weak); into grave and acute (or sharp and flat, or high and low); and into long and short. The management of which is the office of music. Euler is of opinion that no sound making fewer vibrations than thirty in a second,

or more than 7520, is distinguishable by the human ear. According to this doctrine, the limit of our hearing, as to acute and grave, is an mterval of eight octaves.-Tentam. Nov. Theor. Mus. cap. 1. sect. 13.

The velocity of sound is the same with that of the aerial waves, and does not vary much, whether it go with the wind or against it. By the wind indeed a certain quantity of air is carried from one place to another; and the sound is accelerated while its waves move through that part of the air, if their direction 'be the same as that of the wind. But, as sound moves vastly swifter than the wind, the acceleration it will hereby receive is but inconsiderable; and the chief effect we can perceive from the wind is that it increases and diminishes the space of the waves, so that by the help of it the sound may be heard to a greater distance than otherwise it would.

That the air is the usual medium of sound appears from various experiments in rarefied and condensed air. In an unexhausted receiver a small bell may be heard to some distance; but when exhausted it can scarcely be heard at the smallest distance. When the air is condensed, the sound is louder in proportion to the condensation, or quantity of air crowded in; of which there are many instances in Hauksbee's experiments, in Dr. Priestley's, and others. Besides, sounding bodies communicate tremors to distant bodies; for example, the vibrating motion of a musical string puts others in motion, whose tension and quantity of matter dispose their vibrations to keep time with the pulses of air propagated from the string that was struck. Galileo explains this phenomenon by observing that a heavy pendulum may be put in motion by the least breath of the mouth, provided the blasts be often repeated, and keep time exactly with the vibrations of the pendulum; and also by the like art in raising a large bell.

It is not air alone that is capable of the impressions of sound, but water also; as is manifest by striking a bell under water, the sound of which may plainly enough be heard, only not so loud, and also a fourth deeper, according to goo judges in musical notes. And Mersenne says, a sound made under water is of the same tone or note as if made in air and heard under the water.

The velocity of sound, or the space through which it is propagated in a given time, has been very differently estimated by authors who have written concerning this subject. Roberval states it at the rate of 560 feet in a second; Gassendus at 1473; Mersenne at 1474; Duhamel, in the History of the Academy of Sciences at Paris, at 1338; Newton at 968; Derham, in whose measure Flamsteed and Halley acquiesce, at 1142. The reason of this variety is ascribed by Derham partly to some of those gentlemen using strings and plummets instead of regular pendulums; and partly to the too small distance between the sonorous body and the place of observation; and partly to no regard being had to the winds. But by the accounts since published by M. Cassini de Thury, in the Memoirs of the Royal Aca demy of Sciences at Paris, 1738, where cannon were fired at various as well as great distances,

under many varieties of weather, wind, and other circumstances, and where the measures of the different places had been settled with the utmost exactness, it was found that sound was propagated, on a medium, at the rate of 1038 French feet in a second of time. But the French foot is in proportion to the English as fifteen to sixteen; and consequently 1038 French feet are equal to 1107 English feet. Therefore the difference of the measures of Derham and Cassini is thirtyfive English feet, or thirty-three French feet, in a second. The medium velocity of sound therefore is nearly at the rate of a mile, or 5280 feet, in four seconds and two-thirds, or a league in fourteen seconds, or thirteen miles in a minute. But sea miles are to land nearly as seven to six; and therefore sound moves over a sea mile in five seconds and one-third nearly, or a sea league in sixteen seconds. Farther, it is a common observation, that persons in good health have about seventy-five pulsations, or beats of the artery at the wrist, in a minute; consequently in seventy-five pulsations sound flies about thirteen land miles, or eleven sea miles and oneseventh, which is about one land mile in six pulses, or one sea mile in seven pulses, or a league in twenty pulses. Hence the distance of objects may be found by knowing the time employed by sound in moving from those objects to an observer. For example, on seeing the flash of a gun at sea, if fifty-four beats of the pulse at the wrist were counted before the report was heard; the distance of the gun will easily be found by dividing fifty-four by twenty, which gives 2-7 leagues, or about eight miles.

In an ingenious treatise, published 1790, by Mr. G. Saunders, on theatres, he relates many experiments made by himself on the nature and propagation of sound; and shows the great effect of water, and some other bodies, in conducting of sound, probably by rendering the air more dense near them. Some of his conclusions and observations are as follow:-Earth may be supposed to have a twofold property with respect to sound. Being very porous it absorbs sound, which is counteracted by its property of conducting sound, and occasions it to pass on a plane, in an equal proportion to its progress in air, unencumbered by any body. If a sound be sufficiently intense to impress the earth in its tremulous quality, it will be carried to a considerable distance, as when the earth is struck with any thing hard, as by the motion of a car riage, horses' feet, &c. Plaster is proportionally better than loose earth for conducting sound as it is more compact. Clothes of every kind, particularly woollen cloths, are very prejudicial to sound their absorption of sound may be compared to that of water, which they greedily imbibe.

A number of people seated before others, as in the pit or gallery of a theatre, do considerably prevent the voice reaching those behind; and hence it is that we hear so much better in the front of the galleries, or of any situation, than behind others, though we may be nearer to the speaker. Our seats, rising so little above each other, occasion this defect, which would be remedied could we have the seats to rise their

whole height above each other as in the ancient theatres. Paint has generally been thought unfavorable to sound, from its being so to musical instruments, whose effects it quite destroys. Musical instruments mostly depend on the vibrative or tremulous property of the material, which a body of color hardened in oil must very much alter; but we should distinguish that this regards the formation of sound, which may not altogether be the case in the progress of it.

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Water has been little noticed with respect to its conducting sound; but it will be found to be of the greatest consequence. I had often,' says our author, perceived in newly-finished houses that, while they were yet damp, they produced echoes; but that the echoing abated as they dried. When I made the following experiment there was a gentle wind; consequently the water was proportionally agitated. I chose a quiet part of the river Thames, near Chelsea Hospital, and with two boats tried the distance the voice would reach. On the water we could distinctly hear a person read at the distance of 140 feet, on land at that of seventy-six. It should be observed that on land no noise intervened; but on the river some noise was occasioned by the flowing of the water against the boats: so that the difference on land and on water must be much more.'

'Watermen observe that when the water is still, and the weather quite calm, if no noise intervene, a whisper may be heard across the river; and that with the current it will be carried to a much greater distance, and vice versâ against the current. Mariners well know the difference of sound on sea and land.

'When a canal of water was laid under the pit floor of the theatre of Argentino, at Rome, a surprising difference was observed; the voice has since been heard at the end very distinctly, where it was before scarcely distinguishable. It is observable that, in this part, the canal is covered with a brick arch, over which there is a quantity of earth, and the timber floor over all. The villa Simonetta near Milan, so remarkable for its echoes, is entirely over arcades of water. Another villa near Rouen, remarkable for its echo, is built over subterraneous cavities of water. A reservoir of water domed over, near Stanmore, has a strong echo.

I do not remember ever being under the arches of a stone bridge that did not echo; which is not always the case with similar structures on land. A house in Lambeth Marsh, inhabited by Mr. Turtle, is very damp during winter, when it yields an echo which abates as the house becomes dry in summer.' Kircher observes that echoes repeat more by night than during the day; he makes the difference to be double. Dr. Plott says the echo in Woodstock park repeated seventeen times by day, and twenty by night. And Addison's experiment at the villa Simonetta was in a fog, when it produced fifty-six repetitions.

'After all these instances I think little doubt can remain of the influence water has on sound; and I conclude that it conducts sound more than any other body whatever. After water, stone may be reckoned the best conductor of sound. To what cause it may be attributed I leave to

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'Brick, in respect to sound, has nearly the same properties as stone. Part of the garden wall of the late W. Pitt, esq., of Kingston in Dorsetshire, conveys a whisper to the distance of nearly 200 feet.

"Wood is sonorous, conductive, and vibrative; of all materials it produces a tone the most agreeable and melodious; and it is therefore the fittest for musical instruments, and for lining of rooms and theatres. The common notion that whispering at one end of a long piece of timber would be heard at the other end, I found by experiment to be erroneous. A stick of timber sixty-five feet long being slightly struck at one end, a sound was heard at the other, and the tremor very perceptible: which is easily accounted for when we consider the number or length of the fibres that compose it, each of which may be compared to a string of catcut.'

SOUNDS are distinguished, with regard to music, into simple and compound, and that two ways. In the first, a sound is said to be compound, when a number of successive vibrations of the sonorous body, and the air, come so fast upon the ear that we judge them the same continued sound; as in the phenomenon of the circle of fire, caused by putting the fire-end of a stick in a quick circular motion; where, supposing the end of the stick in any point of the circle, the idea we receive of it there continues till the impression is renewed by a sudden return. A simple sound, with regard to this composition, should be the effect of a single vibration, or of so many vibrations as are necessary to raise in us the idea of sound. In the second sense of composition, a simple sound is the product of one voice, or one instrument, &c. A compound sound consists of the sounds of several distinct voices or instruments, all united in the same individual time and measure of duration, that is, all striking the ear together, whatever their other differences may be. But in this sense, again, there is a two-fold composition; a natural and an artificial one.

Natural composition is that proceeding from the manifold reflections of the first sound from adjacent bodies, where the reflections are not so sudden as to occasion echoes, but are all in the same tune with the first note. Artificial composition, which alone comes under the musician's province, is that mixture of several sounds which, being made by art, the ingredient sounds are separable and distinguishable from one another. In this sense the distinct sounds of several voices or instruments, or several notes of the same instrument, are called simple sounds, in contradistinction to the compound ones, in which, to answer the end of music, the simples must have such an agreement in all relations, chiefly as to acuteness and gravity, as that the ear may receive the mixture with pleasure.

Another distinction of sounds with regard to music is that by which they are said to be smooth and even, or rough and harsh, also clear and hoarse the cause of which differences de

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Smooth and rough sounds depend principally on the sounding body; of these we have a notable instance in strings that are uneven, and not of the same dimension or constitution throughout. Perrault, to account for roughness and smoothness, maintains, there is no such thing as a simple sound; but that the sound of the same chord or bell is a compound of the sounds of the several parts of it; so that where the parts are homogeneous, and the dimensions or figure uniform, there is always such a perfect mixture and union of all the sounds as makes one uniform and smooth sound: contrary conditions produce harshness. In effect, a likeness of parts and figure make a uniformity of vibra tions, by which a great number of similar and coincident motions conspire to fortify and im prove each other, and unite, for the more effectual producing of the same effect. This account he confirms from the phenomenon of a bell which differs in tone according to the part it is struck in; and yet, strike it any where, there is a motion over all the parts. Hence he considers the bells as composed of an infinite number of rings, which, according to their different dimensions, have different tones, as chords or strings of different lengths have; and, when struck, the vibrations of the parts immediately struck specify the tone, being supported by a sufficient number of consonant tones in other parts. This must be allowed, that every note of a stringed instrument is the effect of several simple sounds; for there is not only the sound resulting from the motion of the string, but that from the motion of the parts of the instrument, which has a considerable effect in the total sound, as is evident from hence that the same string on different violins sounds very differently.

But Perrault affirms the same of every string without considering the instrument. Every part of the string, he says, has its particular vibrations, different from the gross and sensible vibrations of the whole; and these are the causes of different motions and sounds in the particles, which uniting compose the whole sound of the string, and make a uniform composition, in which the tone of the particular part struck prevails, and all the others mix under a due subordination with it, so as to make the composition smooth and agreeable. If the parts be unevenly or irregularly constituted, the sound is harsh; which is the case in what we call false strings, and various other bodies, which, for this reason, have no certain and distinct tone, but a composition of several tones, which do not unite and mix, so as to have one predominant to specify the total tone. As to clear and hoarse sounds, they depend on circumstances that are accidental to the sonorous body; thus, a voice and instru ment will be hollow and hoarse, if raised within an empty hogshead, that yet is clear and bright out of it: the effect is owing to the mixture of other and different sounds, raised by reflections, which corrupt and change the species of the primitive sounds. For sounds to be fit to obtain

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the end of music, they ought to be smooth and clear, possessing especially the first quality since, without this, they cannot have one certain and discernible tone. Dr. Burney remarks that enquiries concerning the absolute production and modification of sound belong to physics; whereas a musician only examines sounds comparatively one with the other, and' considers their proportions and relation as divided into concords and discords.

The SOUNDBOARD is the principal part of an organ. This soundboard, or summer, is a reservoir into which the wind, drawn in by the bellows, is conducted by a port vent, and thence distributed into the pipes placed over the holes of its upper part. This wind enters them by valves, which open by pressing upon the stops or keys, after drawing the registers, which prevent the air from going into any of the other pipes beside those it is required in.

SOUNDBOARD, or SOUNDING-BOARD,, denotes also a thin broad board placed over the head of a public speaker, to enlarge and extend or strengthen his voice. Soundboards, in theatres, are found by experience to be of no service; their distance from the speaker being too great to be impressed with sufficient force. But soundboards immediately over a pulpit have often a good effect, when made of a just thickness, and according to certain principles.

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SOUNDING, the operation of trying the depth of the sea, and the nature of the bottom, by means of a plummet sunk from a ship to the bottom. There are two plummets used for this pose in navigation, one of which is called the hand-lead, weighing about eight or nine pounds, and the other the deep sea-lead, which weighs from twenty-five to thirty pounds. Both are shaped like the frustum of a cone or pyramid. The former is used in shallow waters, and the latter at a great distance from the shore; particularly on approaching the land after a sea voyage. Accordingly the lines employed for this purpose are called the deep-sea lead-line, and the hand lead-line. The hand lead-line, which is usually twenty fathoms in length, is marked at every two or three fathoms; so that the depth of the water may be ascertained either in the day or night. At the depth of two and three fathoms there are marks of black leather; at five fathoms there is a white rag; at seven a red rag; at ten black leather; at thirteen black leather; at fifteen a white rag; and at seventeen a red ditto. Sounding with the hand-lead, which is called heaving the lead by seamen, is generally performed by a man who stands in the main chains to windward. Having the line quite ready to run out without interruption, he holds it nearly at the distance of a fathom from the plummet; and having swung the latter backwards and forwards three or four times in order to acquire the greater velocity, he swings it round his head, and thence as far forward as is necessary; so that, by the lead's sinking whilst the ship advances, the line may be almost perpendicular when it reaches the bottom. The person sounding then proclaims the depth of the water in a kind of song resembling the cries of hawkers in a city. Thus if the mark of five fathoms is close to the surface of the

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water, he calls, By the mark five!' and as there is no mark at four, six, eight, &c., he estimates those numbers, and calls, ‘By the dip four,' &c. If he judges it to be a quarter or a half more than any particular number, he calls, And a quarter five!' And a half four !' &c. If he conceives the depth to be three-quarters more than a particular number, he calls it a quarter less than the next: thus, at four fathoms and threefourths he calls, A quarter less five!' and so on. The deep sea-lead is marked with two knots at twenty fathoms, three at thirty, four at forty, and so on to the end. It is also marked with a single knot in the middle of each interval, as at twenty-five, thirty-five, forty-five fathoms, &c. To use this lead more effectually at sea, or in deep water on the sea-coast, it is usual previously to bring to the ship, in order to retard her course; the lead is then thrown as far as possible from the ship on the line of her drift, so that, as it sinks, the ship drives more perpendicularly over it. The pilot, feeling the lead strike the bottom, readily discovers the depth of the water by the mark on the line nearest its surface. The bottom of the lead being also well rubbed over with tallow retains the distinguishing marks of the bottom, as shells, ooze, gravel, &c., which naturally adhere to it. The depth of the water, and the nature of the ground, which is called the soundings, are carefully marked in the log-book, as well to determine the distance of the place from the shore as to correct the observations of former pilots.

SOUND POST, a post placed withinside of a violin, &c. as a prop between the back and the belly of the instrument, and nearly under the bridge.

SOUP, n. s. Sax. ruppa; Fr. soupe; Swed. soppa. Strong broth; a decoction of flesh for the table.

Spongy morells in strong ragouts are found, And in the soup the slimy snail is drowned.

Gay's Trivia.

Let the cook daub the back of the footman's new livery; or, when he is going up with a dish of soup, let her follow him softly with a ladle full. Swift.

SOUP, PORTABLE, or DRY SOUP, is a kind of cake formed by boiling the gelatinous parts of animal substances till the watery parts are evaporated. This species of soup is chiefly used at sea, and has been found of great advantage. The following is a receipt to prepare it : of calves feet take four; leg of beef twelve pounds; knuckle of veal three pounds; and leg of mutton ten pounds. These are to be boiled in a sufficient quantity of water, and the scum taken off as usual; after which the soup is to be separated from the meat by straining and pressure. The meat is then to be boiled a second time in other water; and the two decoctions, being added together, must be left to cool, in order that the fat may be exactly separated. The soup must then be clarified with five or six whites of eggs, and a sufficient quantity of common salt added. The liquor is then strained through flannel, and evaporated on the water-bath to the consistence of a very thick paste; after which it is spread rather thin upon a smooth stone, and cut into cakes, and lastly dried in a stove until it becomes

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