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positions, figures, colours. The prospect more appropriate, or more mechanical? If from Hampstead-hill is compressed into it be overlooked by the observer of nature, the compass of a six-pence, yet circum- it can only be because it is obvious and fa stantially represented." A stage coach, miliar. This is a tendency to be guarded travelling at its ordinary speed for half against. We pass by the plainest inan hour, passes, in the eye, only over one stances, whilst we are exploring those twelfth of an inch, yet is this change of which are rare and curious ; by which place in the image distinctly perceived conduct of the understanding, we somethroughout its whole progress; for it is times neglect the stroagest observations, only by means of that perception that the being taken up with others, which, though motion of the coach itself is made sensi- more recondite and scientific, are, as solid ble to the eye. If any thing can abate arguments, entitled to much less consiour admiration of the smallness of the deration, visual tablet compared with the extent of In order to keep the eye moist and vision, it is a reflection which the view of clean (which qualities are necessary to its nature leads us, every hour, to make, brightness and its use), a wash is conviz. that, in the hands of the Creator, stantly supplied by a secretion for the purgreat and little are nothing.
pose; and the superfluous brine is conSturmius held, that the examination of veyed to the nose through a perforation in the eye was a cure for atheism. Besides the bone as large as a goose-quill
. When that conformity to optical principles which once the fluid bas entered the nose, it its internal constitution displays, and spreads itself upon the inside of the noswhich alone amounts to a manifestation tril, and is evaporated by the current of of intelligence having been exerted in the warm air, which, in the course of respirastructure; besides this, which forms, no tion, is continually passing over it. Can doubt, the leading character of the organ, any pipe or outlet, for carrying off the there is to be seen, in every thing belong- waste liquor from a dye-house or a dising to it and about it, an extraordinary tillery, be more mechanical than this is? degree of care, an anxiety for its preser- It is easily perceived, that the eye must vation, due, if we may so speak, to its want moisture ; but could the want of the value and its tenderness. It is lodged in eye generate the gland which produces a strong, deep, bony socket, composed the tear, or bore the hole by which it is by the junction of seven different bones*, discharged,-a hole through a bone ? hollowed out at their edges. In some few It is observable, that this provision is species, as that of the coatimondi +, the not found in fish, -the element in which orbit is not bony throughout; but when they live supplying a constant lotion to ever this is the case, the upper, which is the eye. the deficient part, is supplied by a cartila- It were, however, injustice to dismiss ginous ligament; a substitution which the eye as a piece of inechanism, without shows the same care. Within this socket noticing that most exquisite of all conit is imbedded in fat, of all animal sub- trivances, the nictitating membrane, which stances the best adapted both to its repose is found in the eyes of birds and of many and motion. It is sheltered by the eye- quadrupeds. Its use is to sweep the eye, , brows; an arch of hair, which, like a which it does in an instant, to spread over thatched penthouse, prevents the sweat it the lachrymal humour; to defend it and moisture of the forehead from running also from sudden injuries; yet not totally, down into it.
when drawn upon the pupil, to shut out But it is still better protected by its lid. the light. The commodiousness with Of the superficial parts of the animal which it lies folded up in the upper corner frame, I know none which, in its office of the eye, ready for use and action, and and structure, is more deserving of atten. the quickness with which it executes its tion than the eyelid. It defends the eye; purpose, are properties known and obviit wipes it; it closes it in sleep. Are ous to every observer; but what is equally there, in any work of art whatever, pur- admirable, though not quite so obvious, poses more evident than those which this is the combination of two kinds of suborgan fulfils ? or an apparatus for exe- stance, muscular and elastic, and of two cuting those purposes more intelligible, different kinds of action, by which the
* Heister, sect. 89.
+ Mem. R. Ac. Paris, p. 117.
motion of this membrane is performed. pulley. This is a peculiarity; and obIt is not, as in ordinary cases, by the serve the advantage of it. A single musaction of two antagonist muscles, one cle with a straight tendon, which is the pulling forward and the other backward, common muscular form, would have been that a reciprocal change is effected; but sufficient, if it had had power to draw far it is thus: The membrane itself is an enough. But the contraction, necessary elastic substance, capable of being drawn to draw the membrane over the whole out by force like a piece of elastic gum, eye, required a longer muscle than could and by its own elasticity returning, when lie straight at the bottom of the eye. the force is removed, to its former posi- Therefore, in order to have a greater tion. Such being its nature, in order to length in a less compass, the cord of the fit it up for its office, it is connected by a main muscle makes an angle. This, so tendon or thread with a muscle in the far, answers the end; but, still farther, it back part of the eye: this tendon or makes an angle, not round a fixed pivot, thread, though strong, is so fine, as not but round a loop formed by another musto obstruct the sight, even when it passes cle; which second muscle, whenever it across it; and the muscle itself, being contracts, of course iwitches the first placed in the back part of the eye, derives muscle at the point of inflection, and from its situation the advantage, not only thereby assists the action designed by both. of being secure, but of being out of the One question may possibly have dwelt way; which it would hardly have been in in the reader's mind during the perusal of any position that could be assigned to it these observations, namely, Why should in the anterior part of the orb, where its not the Deity have given to the animal function lies. When the muscle behind the faculty of vision at once? Why this the eye contracts, the membrane, by circuitous perception; the ministry of so means of the communicating thread, is many means; an element provided for the instantly drawn over the fore-part of it. purpose; reflected from opaque substanWhen the muscular contraction (which is ces, refracted through transparent ones; a positive, and, most probably, a volun- and both according to precise laws; then, tary effort) ceases to be exerted, the elas- a complex organ, an intricate and artifiticity alone of the membrane brings it cial apparatus, in order, by the operation back again to its position *. Does not of this element, and in conformity with this, if any thing can do it, bespeak an the restrictions of these laws, to produce artist, master of his work, acquainted an image upon a membrane communicawith his materials? “Of a thousand other ting with the brain ? Wherefore all this? things," say the French Academicians, Why make the difficulty in order to surwe perceive not the contrivance, because mount it? If to perceive objects by so
some we understand them only by the effects, other mode than that of touch, or objects of which we know not the causes: but which lay out of the reach of that sense, we here treat of a machine, all the parts were the thing proposed; could not a whereof are visible; and which need only simple volition of the Creator have combe looked upon, to discover the reasons municated the capacity ? Why resort to of its motion and action t."
contrivance, where power is omnipotent? In the configuration of the muscle Contrivance, by its very definition and which, though placed behind the eye, nature, is the refuge of imperfection. To draws the nictitating membrane over the have recourse to expedients, implies diffieye, there is, what the authors, just now culty, impediment, restraint, defect of quoted, deservedly call a marvellous me- power. This question belongs to the chanism. I suppose this structure to be other senses, as well as to the sight; to the found in other animals; but, in the me- general functions of animal life, as putrimoirs from which this account is taken, it tion, secretion, respiration; to the æcois anatomically demonstrated only in the nomy of vegetables; and indeed to alcassowary. The muscle is passed through most all the operations of nature. The a loop formed by another muscle; and is question, therefore, is of very wide exthere infected, as if it were round a tent; and amongst other answers which
* Philos. Transact 1796.
+ Memoirs for a Natoral History of Animals, by the Royal Academy of Sciences at Paris, done into English by Order of the Royal Society, 1701, page 249.
may be given to it, besides reasons of ranks of these. We do not advance this which probably we are ignorant, one an- a doctrine either of philosophy or of swer is this : It is only by the display of religion; but we say that the subject may contrivance, that the existence, the agency, safely be represented under this view; the wisdom of the Deity, could be testi- because the Deity, acting himself by fied to his rational creatures. This is the general laws, will have the same consescale by which we ascend to all the know- quences upon our reasoning, as if he had ledge of our Creator which we possess, prescribed these laws to another. It has so far as it depends upon the phænomena, been said, that the problem of creation or the works of nature. Take away this, was, “attraction and matter being given, and you take away from us every subject to make a world out of them :" and, as of observation, and ground of reasoning; above explained, this statement perhaps I mean as our rational faculties are formed does not convey a false idea. at present. Whatever is done, God We have made choice of the eye as an could have done without the intervention instance upon which to rest the argument of instruments or means : but it is in the of this chapter. Some single example construction of instruments, in the choice was to be proposed : and the eye offered and adaptation of means, that a creative itself under the advantage of admitting of intelligence is seen. It is this which consti- & strict comparison with optical instru
a tutes the order and beauty of the universe. ments. The ear, it is probable, is no God, therefore, has been pleased to pre- less artificially and mechanically adapted scribe limits to his own power, and to to its office than the eye. But we know work his ends within those limits. The less about it: we do not so well undergeneral laws of matter have perhaps the stand the action, the use, or the mutual nature of these limits ; its inertia, its re- dependency of its internal parts. Its action; the laws which govern the com- general form, however, both external and munication of motion, the refraction and internal, is sufficient to show that it is an reflection of light, the constitution of instrument adapted to the reception of fluids, non-elastic and elastic, the trans- sound ; that is to say, already knowing mission of sound through the latter; the that sound consists in pulses of the air, laws of magnetism, of electricity; and we perceive, in the structure of the ear, a probably others, yet undiscovered. These suitableness to receive impressions from are general laws; and when a particular this species of action, and to propagate purpose is to be effected, it is not by these impressions to the brain. For of making a new law, nor by the suspension what does this structure consist ? An exof the old ones, nor by making them ternal ear (the concha), calculated, like wind, and bend, and yield to the occa- an ear-trumpet, to catch and collect the sion (for nature with great steadiness pulses of which we have spoken ; in large adheres to and supports them); but it is, quadrupeds, turning to the sound, and as we have seen in the eye, by the inter- possessing a configuration, as well as position of an apparatus, corresponding motion, evidently fitted for the office: of with these laws, and suited to the exi- a tube which leads into the head, lying at gency which results from them, that the the root of this outward ear, the folds purpose is at length attained.
As we and sinuses thereof tending and conducthave said, therefore, God prescribes limits ing the air towards it: of a thin memto his power, that he may let in the exer- brane, like the pelt of a drum, stretched cise, and thereby exhibit demonstrations, across this passage upon a bony rim: of a of his wisdom. For then, ¿. e. such chain of moveable, and infinitely curious laws and limitations being laid down, it is bones, forming a communication, and the as though one Being should have fixed only communication, that can be observed, certain rules; and, if we may so speak, between the membrane last mentioned and provided certain materials; and, after the interior channels and recesses of the wards, have committed to another Being, skull: of cavities, similar in shape and out of these materials, and in subordina- form to wind instruments of music, being tion to these rules, the task of drawing spiral or portions of circles : of the eustaforth a creation : a supposition which evi- chian tube, like the hole in a drum, to let dently leaves room, and induces indeed a the air pass freely into and out of the necessity for contrivance. Nay, there barrel of the ear, as the covering memmay be many such agents, and many brane vibrates, or as the temperature may be altered; the whole labyrinth hewn out diminishing the space through which it of a rock; that is, wrought into the sub- oscillates; both of which changes may sidikce of the hardest bone of the body. augment or facilitate the still deeper action This assemblage of connected parts con- of the auditory nerves. suitutes together an apparatus, plainly The benefit of the eustachian tube to enough relative to the transmission of the organ may be made out upon known sound, or of the impulses received from pneumatic principles. Behind the drum sound, and only to be lamented in not of the ear is a second cavity, or barrel, being better understood.
called the tympanum. The eustachian The communication within, formed by tube is a slender pipe, but sufficient for the small bones of the ear, is, to look the passage of air, leading from this upon, more like what we are accustomed cavity into the back part of the mouth. to call machinery, than any thing I am Now, it would not have done to have had acquainted with in animal bodies. It a vacuum in this cavity; for, in that case, seems evidently designed to continue to- the pressure of the atmosphere from withwards the sensorium the tremulous mo- out would have burst the inembrane which tions which are excited in the membrane covered it. Nor would it have done to of the tympanum, or what is better known bave filled the cavity with lymph or any by the name of the “drum of the ear." other secretion; which would necessarily The compages of bones consists of four, have obstructed, both the vibration of the which are so disposed and so hinge up- membrane, and the play of the small on one another, as that if the membrane, bones. Nor, lastly, would it have done the drum of the ear, vibrate, all the four to have occupied the space with confined are put in motion together; and, by the air, because the expansion of that air by result of their action, work the base of heat, or its contraction by cold, would that which is the last in the series, upon bave distended or relaxed the covering an aperture which it closes, and upon membrane, in a degree inconsistent with which it plays, and which aperture opens the purpose which it was assigned to into the tortuous canals that lead to the execute. The only remaining expedient, brain. This last bone of the four is and that for which the eustacbian tube called the stapes. The office of the drum serves, is to open to this cavity a commuof the ear is to spread out an extended nication with the external air. In one surface, capable ofreceiving the impressions word; it exactly answers the purpose of of sound, and of being put by them into a the hole in a drum. state of vibration. The office of the The membrana tympani itself likewise, stapes is to repeat these vibrations. It is deserves all the examination which can a repeating frigate, stationed more within be made of it. It is not found in the the line. From wbich account of its ears of fish; which furnishes an addiaction may be understood, how the sensa- tional proof of what indeed is indicated tion of sound will be excited, by any by every thing about it, that it is approthing which communicates a vibratory priated to the action of air, or of an motion to the stapes, though not, as in elastic medium. It bears an obvious reall ordinary cases, through the interven- semblance to the pelt or head of a drum, tion of the membrana tympani. This is from which it takes its name. It resemdone by solid bodies applied to the bones bles also a drum-head in this principal of the skull, as by a metal bar holden at property, that its use depends upon its one end between the teeth, and touching tension.
Tension is the state essential to at the other end a tremulous body. It it. Now we know that, in a drum, the likewise appears to be done, in a consi- pelt is carried over a hoop, and braced as derable degree, by the air itself, even occasion requires, by the means of strings when this membrane, the drum of the attached to its circumference. In the ear, is greatly damaged. Either in the membrane of the ear, the same purpose natural or preternatural state of the organ, is provided for, more simply, but not less the use of the chain of bones is to propa- mechanically, nor less successfully, by a gate the impulse in a direction towards different expedient, viz. by the end of the brain, and to propagate it with the a bone (the handle of the malleus) pressadvantage of a lever: which advantage ing upon its centre. It is only in very consists in increasing the force and strength large animals that the texture of this of the vibration, and at the same time membrane can be discerned. In the
Philosophical Transactions for the year any other cover than what was capable, by 1800 (vol. i.), Mr. Everard Home has its texture, of receiving vibrations from given some curious observations upon the sound, and, by its connexion with the inear, and the drum of the ear of an ele- terior parts, of transmitting those vibraphant. He discovered in it, what he tions to the brain, the use of the organ, calls a radiated muscle, that is, straight so far as we can judge, must have been muscular fibres, passing along the mem- entirely obstructed. brane from the circumference to the centre; from the bony rim which surrounds $ 4. Of the succession of Plants and it towards the handle of the malleus to
Animals. which the central part is attached. This The generation of the animal no more muscle he supposes to be designed to bring accounts for the contrivance of the eye or the membrane into unison with different ear, than, upon the supposition stated in a sounds: but then he also discovered, that preceding chapter, the production of a this muscle itself cannot act, unless the watch by the motion and mechanism of a membrane be drawn to a stretch, and kept former watch, would account for the skill in a due state of tightness, by what may and attention evidenced in the watch, so be called a foreign force, viz. the action of produced; than it would account for the the muscles of the malleus. Supposing disposition of the wheels, the catching of his explanation of the use of the parts to their teeth, the relation of the several parts be just, our author is well founded in the of the works to one another, and to their reflection which he makes upon it: “ that common end, for the suitableness of their this mode of adapting the ear to different forms and places to their offices, for their sounds, is one of the most beautiful ap- connexion, their operation, and the useful plications of muscles in the body; the result of that operation. I do insist most mechanism is so simple, and the variety of strenuously upon the correctness of this effects so great."
comparison; that it holds as to every Io another volume of the Transactions mode of specific propagation ; and that above referred to, and of the same year, whatever was true of the watch, under the two most curious cases are related of hypothesis above mentioned, is true of persons who retained the sense of hearing, plants and animals. not in a perfect, but in a very consider- 1. To begin with the fructification of able degree, notwithstanding the almost plants. Can it be doubted but that the total loss of the membrane we have been seed contains a particular organization ? describing. In one of these cases, the. Whether a latent plantule with the means use here assigned to that membrane, of of temporary nutrition, or whatever else it modifying the impressions of sound by be, it encloses an organization suited to the change of tension, was attempted to germination of a new plant. Has the plant be supplied by straining the muscles of which produced the seed any thing more to the outward ear. “ The external ear," do with that organization, than the watch we are told, “had acquired a dis- would have had to do with the structure of tinct motion upward and backward, the watch which was produced in the course which was observable whenever the patient of its mechanical movement? I mean, Hasit listened to any thing which he did not any thing at all to do with the contrivance ? distinctly hear: when he was addressed in The maker and contriver of one watch, a whisper, the ear was seen immediately to when he inserted within it a mechanism move : when the tone of voice was louder, suited to the production of another watch, it then remained altogether motionless." was, in truth, the maker and contriver of
It appears probable, from both these that other watch. All the properties of cases, that a collateral, if not principal, use the new watch were to be referred to his of the membrane, is to cover and protect agency: the design manifested in it, to his the barrel of the ear which lies behind it. intention: the art, to him as the artist: the Both the patients suffered from cold: one, collocation of each part, to his placing: the “ a great increase of deafness from catching action, effect, and use, to his counsel, in. cold;" the other, “ very considerable pain telligence, and workmanship. In producing from exposure to a stream of cold air," it by the intervention of a former watch, he Bad effects therefore followed from this was only working by one set of tools in. cavity being left open to the external air; stead of another. So it is with the plant, yet, bad the Author of nature shut it up by and the seed produced by it. Can any