'l^ College of 3$f^v^icmm anli burgeons ilibrarp Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/physiologicalillOObuch PHYSIOLOGICAL ILLUSTRATIONS ORGAN OF HEARING. PHYSIOLOGICAL ILLUSTRATIONS OF THE ORGAN OF HEARING, MORE PARTICULARLY OF THE SECRETION OF CERUMEN, AND ITS EFFECTS IN RENDERING AUDITOR V PERCEPTION ACCURATE AND ACUTE ; WITH FURTHER REMARKS ON THE TREATMENT OF DIMINUTION OF HEARING, ARISING FROM IMPERFECT SECRETION, &C. BEING A SEQUEL TO THE GUIDE, AND TO THE ILLUSTRATIONS OF ACOUSTIC SURGERY. By THOMAS BUCHANAN, C. M. MEMBER OF THE UNIVERSITY OF GLASGOW ; MEMBER OF THE WERNERIAN NATURAL HISTORY SOCIETY OF EDINBURGH ; HONORARY AND CORRESPONDING MEMBER OF THE MEDICO»CHIRURGICAL SOCIETY OF THE UNIVERSITY OF GLASGOW ; MEMBER OF THE ROYAL MEDICAL SOCIETY, AND CORRESPONDING MEMBER OF THE PHRENOLOGICAL SOCIETY, EDINBURGH, &C. AUTHOR OF THE GUIDE, AND OF THE ILLUSTRATIONS OF ACOUSTIC SURGERY, AND SURGEON TO THE HULL DISPENSARY FOR DISEASES OF THE EYE AND EAR. LONDON : PUBLISHED BY LOXGMAN, REES, ORME, BROWN AND GREEN. 1828.

- burgh Philosophical Journal, January, 182L 47 circle in the meatus, and at the same time promote the secretion of healthy cerumen. After repeated trials I composed a preparation which I have termed Unguentum Auriculares^* and which has been of more temporary benefit to patients with diminu- tion of hearing', arising from imperfect secretion accom- panied with Hirsutus Tubulus, than any medicine which I have used. The first person on whom I tried this new preparation was aa old soldier, who had been almost deaf several years. He had been stationed in the island of St. Domingo, in the year 1795, when after being re- viewed, he laid himself down on the damp grass, and caught a severe cold, which was followed by almost total deafness. Being an excellent soldier, every effort was made by various medical gentlemen to restore his hear- ing, but in vain. He was afterwards discharged, and at the time when he applied to me, subsisted on a small pension and the product of his labour as a shoemaker. The following statement of his case is taken from the Journal. " Hull^ 25th Jaly^ 1826. Richard Potter, aged seventy years, has been under treatment upwards of two weeks ; has had the injection applied, and taken decoc- * For the Formula of which, see Appendix, 48 tion without receiving much benefit. Applied this day the Unguentum Auricular es^ and gave the nervine draught. Patient heard distinctly when spoken to in a low tone of voice, within . fifteen minutes after the ointment was applied and the medicine taken." • Several patients aflfected with the same complaint were treated in a similar manner, and the restoration of their hearing was eflfected as speedily as in the above case. From these fortunate circumstances I was induced to send to Mr. J — n, mentioned in page 43, in order to try the powers of this excellent preparation on him. He arrived in town when I was visiting some patients, and one of my pupils, who was in attendance, spoke to him, and although the young gentleman shouted as loud as he could, he could scarcely make himself heard by the patient. As soon as I arrived, Mr. J. was taken into the surgery, and while my eldest pupil supported his head in the most favourable position, I extracted the greater part of the strong hairs from the meatus, and then applied the ointment with a camel-hair pencil, so as to form an artificial tubular circle. The effect was so instantaneous and satisfactory, that I called the pupil into the room who had spoken to him 49 on his arrival, in order to witness the resuH of the appli- cation, and who expressed as much astonishment as the patient did of satisfaction. I then took Mr. J. into the apartment appropriated to the Dispensary, where upwards of a dozen patients were seated, all of whom viewed the case with unfeigned satisfaction ; for in him, they beheld a pledge of their future restoration. * In order to melt the ointment so that it may be applied with a small brush as described, and at the same time the preparation may lose as little as possible of its stimu- lating qualities, I generally heat a small plate, and place a little of the ointment on it, immediately previous to application. This ointment should be prepared, if pos- sible, just before application, otherwise, its effects are much diminished ; and if exposed to the atmosphere for any length of time, it becomes quite inert, owing- to the volatile particles being easily dissipated. I have thus shewn, that if a patient affected with diminution of hearing arising from imperfect secretion, fSecretio Imperfecta] were to take the draught men- tioned,j' and a preparation containing- the properties of * Oue of these patients was upwards of fifty years of age, and during tlie last twenty years had great diminution of hearing ; on the application of the Unguenta, (No. 1. and No. 2. mixed) so as to form the tubular circle, the patient could hear distinctly in the space of ten minutes after the operation, t For the Formula of which, see Appendix. H 50 healthy cerumen were to be applied in the manner described, so as to form a tubular circle, the hearing- would be restored ; but the patient would be unable to hear for a few minutes after the operation, until the stimulus of the medical preparation had excited the nervous fasciculi, in, and around the tube, so as to excite the action of the membrana tympani, in order that it might accommodate itself to the pulsations, and thence transmit the undulatory vibrations to the sentient parts of the organ. The absorption of the resilient pulsations of sound, will be speedily effected by means of the medicated tubular circle, and consequently, accurate vibrations of the membrana tympani take place. But if, instead of the medicated preparation, healthy cerumen, recently extracted, were to be applied to the dry tube, the patient would be more quickly restored to his hearing, than by any imitation, however accurately prepared ; and the hearing would continue as long as the stimulus of the application existed. The objection to this mode of treatment would be, the difficulty of procuring a sufficient quantity of healthy cerumen recently extracted. And likewise the danger there might be of communicating to the patient, any disease with which the person might be affected, from 51 whom the cerumen was extracted, or, at least convey some peculiarity of diathesis to contaminate, or perhaps destroy the healthy secreting power of the ceruminous glands. Even the simple act of washing the meatus with an injection of tepid water, will cause a partial, but tem- porary restoration of hearing ; provided no more fluid remain in the tube, than that which is necessary to lubri- cate the meatus. The tepid water stimulating the ceru- minous glands partially, and dissolving the cerumen that may be in, or which may be squeezed out of the ducts, by the action of elongating the auricle during the opera- tion of cleaning the meatus, may cause partial excretion, and this excretion forming an aqua-ceruminous tubular circle, is the cause of the temporari/ improvement of hearing, sometimes observable after the operation of syringing the meatus has been performed. But if the medicated, or pyrolignous injection,* were used, it would be still more powerful than that of tepid water, and if continued, and assisted by medicine, effect healthy action in the parts, so as to produce secre- tion and excretion, improve, and ultimately restore the ceruminous tubular circle. * For the Formula of which, see Illustrations of Acoustic Surgery, page 103. h2 52 As all glutinous aromatic substances are more or less volatile, according- to the greater or lesser quantity of odoriferous particles contained in them, and the degree of heat to which they may be exposed ; so it will be found, that the cerumen when volatilized and thrown off by the heat of the parts in the healthy subject, serves likewise another useful purpose, as well as those mentioned, and which will be explained when we recollect the situation and structure of the membrana tympani, as has been already described.* The existence of the membrana tympani, is so essential to the arrangement of the healthy organ, that when destroyed either by disease or accident, no contrivance hitherto invented, has been able to preserve the tym- panum effectually from the baneful effects of a moist, cold atmosphere, when the parts have been long exposed to its influence. •]■ * For a description of the membrana tympani in the human subject, see page 8 of this work. f The destruction of the membrana tympani, may be effected by the process of ulceration, the introduction of foreign bodies, or ruptured, sometimes, but rarely, by the concussion or intensity of atmospheric undulations, produced by the firing of cannon ; but in all cases, the destruction or even partial loss of this membrane, is productive of consequences fatal to perfect hearing. I have frequently seen patients who have heard remarkably acute, in whom the membrana tympani of one ear was destroyed, but it was only by means of the healthy ear, that this acuteness qfhearinff was effected. 53 Inflammation and ulceration, are the frequent eon- sequences of exposure to cold moist winds ; and if the indication of cure be not clearly understood, and means adapted to prevent the progress of disease in its incipient stage, irremediable destruction of the parts will, perhaps, ultimately follow, accompanied with Inhahilitas, the most hopeless and deplorable of all diseases that affect this organ * The destruction of the membrana tympani has, how- ever, been mentioned by authors as trivial, and in no way affecting or diminishing the hearing ; but on the contrary, that those persons in whom the membrane was destroyed, had notwithstanding, retained their perfect hearing. Sir Everard Home, in his " Additional remarks '^ on Sir Astley Cooper's paper, " On the effects which take place from the destruction of the membrana tympani,^'-]- asserts, " that in cases in which the membrana tympani has been destroyed, the air is capable of acting with sufficient force on the stapes^ to communicate vibrations to it, and to produce on the internal organ, the necessary effect for perfect hearings is completely ascertained by * See the Synoptical Table of Diseases of the Human Ear, in the Guide, and in the Illustrations of Acoustic Surgery. t See Philosophical Transactions, 1800. 54 Mr. Cooper's observations/'* If this statement of Sir Everard's were correct, there would be little use for the membrana tympani, and its beautiful muscular struc- ture, by which it accommodates itself to the great variety of sound. But unfortunately for the accuracy of Sir Everard's " additional remarks,'^ Sir Astley, in his state- ment of the case, allows that in Mr. P. there " was a slight degree of deafness ;^^ and afterwards adds, "Ae in- formed me, that in a voyage to the East Indies, while others, when ships were hailed at sea, could catch words with accuracy, his organ of hearing received only an indistinct impression"^ and that in Mr. A.'s case, the " defect of hearing in the diseased organ was somewhat greater " That the power of the undulations of sound may be increased by the speaker, so as to cause the person to hear the words spoken to him, even when the membrana tympani is destroyed, I have no doubt. I have tried it myself, and succeeded. But could the person to whom I spoke, be said to have perfect hearing, because I raised the tone of my voice when speaking to him, and by that means the pulsations of sound became strength- * Some additional remarks to the foregoing, on the mode of hearing in cases where the membrana tympani has been destroyed. By Everard Home, Esq. Philosophical Transactions, 1800. f An excellent criterion of the perfection, or degree of diminution of hearing in the individual, is found in the distance at which perception of sound takes place. 55 ened, and their impulse excited the almost dormant qualities of the sentient parts of the organ, so that perception of sound took place. Surely, if the hearing be diminished, it cannot be perfect. From my own observations on those who have lost the membrana tympani, I am inclined to believe that part* of the statement, in Sir Astley's history of the above cases, where he mentions the apparent diminution of hearing in his patients, in preference to the remarks of Sir Everard ; especially, when I have always found, that the destruction of the membrane, or even when only partially injured, was sooner or later, followed by great diminution of hearing, terminating generally in deafness. The sole intent of Sir Astley's paper, was to reconcile patients, in whom permanent obstruction of the eusta- chian tube had taken place, to the operation of puncturing the membrana tympani, in order to restore the hearing, when there existed no other cause of obstruction to auditory perception. But the operation is only the lesser * I mention this part, because in several other parts of that excellent paper, the assertions of the worthy Baronet disagree with my own observations ; especially, where he mentions " an accumulation of the natural secretion, or wax," taking place in the meatus of an individual, whose membrana tympani had been destroyed, and in whom the destructive process of ulceration had formerly existed several years prior to his statement of the case ; but of which I shall notice in its proper place. 36 evil, and must on that account, be depreciated, if there remain any other mode of treatment by which the hear- ing can be restored * Every circumstance connected with the welfare of this membrane, must therefore be invaluable, inasmuch, as its loss sooner or later, exposes the tympanum and internal parts of the ear, to be annoyed by every passing blast and hurricane. And althouofh this membrane should neither be destroyed by disease nor accident, yet if it be constantly exposed to the action of an arid, cold atmosphere, and the ceruminous glands become destitute of their secreting power, or nearly so, the membrane becomes shrunk and colapsed, diaphanous and shining, sometimes trans- parent as if divested of vitality, and diminution of hearing, generally followed by deafness, is the result of a continued want of this secretion. The plentiful secretion of healthy cerumen, is therefore of the utmost consequence towards preserving this mem- brane ; and hence the use of the odoriferous volatilizing particles ; for when the tubular circle is well formed * For an account of this operation, see Surgical Remarks on the Operation of Puncturing the Membrana Tympani, in the Guide to Acoustic Surgery, Chap. II. page 32. 57 and complete, the volatilized odoriferous particles of cerumen, which are thrown off by the heat of the parts, lubricate the external surface of the membrana tympani, and promote circulation in the membrane, by stimulating- it to that healthy tension, consistent with elasticity and vitality, so as to render it efficient to transmit the most delicate vibrations. The volatilized secretion which protects the membrane from the action of cold and dry winds, preserves it likewise from the baneful effects of a cold moist atmos- phere, frequently more prejudicial than that of extreme drought. The moisture or vitiated secretion, produced in the meatus by the admission of the atmosphere, when unprotected by the ceruminous tubular circle, causes the membrana tympani to relax, become thickened and callous, vibrating only to the impulse of very strong- puL sations. For it may be remarked, that the membrane, when in a relaxed state, cannot vibrate so easily as when it is tense and stimulated.* Sir Everard Home, in his excellent paper formerly mentioned, ascribes accuracy of hearing entirely to the muscular structure of the membrana tympani ; without assigning any properties to the cerumen, either in stimu- lating the membrane, modifying or absorbing the resilient pulsations of sound. * The stripgs cf a violin, when damp and relaxed, furnish a fine illustratioji of this ajciom, I 58 He seems to have had no idea of the properties of cerumen in rendering auditory perception accurate^ by means of the absorption of resilient pulsations. " The knowledge of a muscular structure in the membrana tympani," says that celebrated author, "enables us to explain many phenomena in hearing, which have not hitherto been accounted for in a satisfactory manner. It is principally by means of this muscle, that accurate perceptions of sound are communicated to the internal organ,* and that the membrana tympani is enabled to vary the state of its tension, so as to receive them in the quick succession in which they are conveyed to it." j* The muscular structure of the membrana tympani, is well adapted to communicate grave or acute vibrations to the sentient parts of the organ, but it is only by means of the ceruminous tubular circle^ that accuracy of these vibrations can take place. J * The fallacy of this theory is easily proved by the following circumstances, ■which occur so frequently, that they may be put to the test by any practitioner. When the meatus is divested of cerumen, resilience, or confused, inaccurate audi- tory perception takes place; even although no defect of the membrana tympani exists, yet as soon as the secretion of healthy cerumen is restored, so as to form the ceruminous tubular circle; or, if only an artificial one be formed, accurate percep- tion oj" sound takes place, unless the tympanum, labyrinth, or sentient parts of the organ be injured. f Croonian Lecture, on the Structure and Uses of the Membrana Tympani of the Ear.. By Evcrard Home, Esq. F.R.S. Anno 1800.— Philosophical Trans. Vol. 90. % See pages 6, 17, 19, and 30 of this work. 59 M. Du Verney, as has been already noticed, ascribed to the membrane, the power of accommodating- it- self to grave and acute sounds ; but afterwards adds, " I confess it is hard to conceive how this is performed, they are mechanical motions which are imperceptible, the nature and causes of which are difficult to explain.* M. Savart affirms •]• " that it is not necessary to suppose, as has been done, the existence of a particular me- chanism, intended to act on the membrane of the tympanum, and make it vibrate in unison with the bodies which affect it ; but, that it is always so conditioned, as to be readily influenced by any number of vibrations /^+ That it is always so, I deny ;|1 or how is it, that when a person is intensely thinking on any subject, another person may approach him, and even speak in his ordi- nary tone of voice, and not be heard. The will is there- fore always necessary, to enable a person to discriminate between the various tones of pulsations, which may * Treatise on the Organ of Hearing. f Ann. de Chim. Vol. XXVI. J Although these authors ascribe no qualities to the cerumen, whereby it may contribute towards exciting healthy action, so as to produce tension of the fibres of the membrana tympani, yet, without its protecting influence, to guard and defend the meatus, and also to modify the undulations of sound, before they approach to the membrane, as well as its stimulating properties, the membrana tympani would soon become callous, or painfully acute by the stimulus of these undalalions ; and even then, fail in transmitting accurate vibratory sensation, unless the resilient pulsations be absorbed by the ceruminous tubular circle. II As an analogical proof, see Plates V., VI., and VII. i2 60 affect the membrana tympani, in order to form accurate perception of hearing. I grant that a person may be roused from abstraction of thought, but even then, he cannot distinguish the tones and various inflections of sound, until he make an effort for the purpose ; which is done so quickly, as to catch the pulsations from the vibrating body, before it becomes quiescent- That the mil is necessary, may be also inferred from the number and functions of the nerves which supply the parts.* The chorda tympani stretches across, and is con- nected with the membrana tympani and ossicula auditus. The meatus is also plentifully supplied with branches from the fifth, portio dura, the second, and sometimes the first vertebral nerves. The portio dura, from its connection with the membrana tympani by means of its branch the chorda, tympani, must have considerable influence in as- * Mr. Bell, in an admirable paper read before the Royal Society, says, " A pure or simple nerve has the influence propagated along with it in one direction only, and not backwards and forwards; it has no reflected operation or power retro- gade; it does not both act /rom and to the senioxmra,"— Philosophical Transactions, Part II. page 163, 1826. This beautiful and simple theory of the nervous system, is greatly in favour of the muscular structure of the membrana tympani. For if a branch of the great moter nerve be distributed in the membrane, it ought, agreeable to the functions of moter nerves, to furnish the membrana tympani with a power to produce tension, and tension is generally understood to be accomplished by the contraction of fibres, a property or quality inherent in the muscvilar fibre, under the influence of a particular nerve. 61 sisting to promote the healthy tension of the membrane, So as to dispose it to transmit acute vibrations from sonorous bodies. And as all undulatory motion, whether of aerial or denser mediums, is preceded by more or less of a slight oscilliation, but so quickly followed by the pulsation of sound, as to be scarcely perceptible ; so this avant courier of the pulsation affecting the extreme branches of the nervous fasciculi distributed on the face and lateral parts of the head,* conveys the approach, followed almost instantaneously by the pulsation itself, -j- I say almost instantaneously, because however short the space may be, still it exists as a portion of time. In the same manner, the rays of the sun when travelling to this earth, a distance of upwards of ninety-six millions of miles, perform the journey in seven or eight minutes, which is so rapid, that it is deemed instantaneous ; and yet we know, that seven or eight minutes is a space accounted sometimes too long, especially when occupied * And hence may partially be accounted the quick turn of the head, when sounds are heard indistinctly. f The connection formed between the portio dura and the fifth, by means of the junction of a branch of the latter nerve and the chorda tympani, will account for this seeming retrogade influence. The impression being carried towards the senso- rium by branches of the fifth, or sentient nerve, until the junction with the portio dura, or moter, which immediately acts, so as to promote the necessary degree of tension in the fibres of the membrana tympani.. 62 by painful sensations. The small muscles in the tym- panum, in like manner, act instantaneously, so as to pro- duce general tension of the membrana tympani ; which is rendered still more efficient by the action of the fibres of • the membrane, under the controul of the minute fasciculi of the chorda tympani or semi-moter and semi- sentient nerve. The membrana tympani, is also stimu- lated by the halitus of the ceruminous tubular circle, and by these means it accommodates itself agreeable to the will, or desire of the auditor, to the variety of pulsa- tions produced by the vibration of sonorous bodies, whether grave or acute. It has been remarked by one of our most elegant writers, " that if the stroke be strong, the organ of hearing- suffers a considerable degree of tension. If the stroke be repeated soon after, the repetition causes an expectation of another stroke. And it must be observed that expectation itself causes a ten- sion. This is apparent in many animals, who, when they prepare for hearing any sound, rouse themselves, and prick up their ears ; so that here the effect of the sound is considerably augmented by a new auxiliary, the expectation.'^^ By the term expectation, it may be presumed the author meant the will of the auditor ; which is communicated by the branches of * Burke on the Sublime and Beautiful, Part TV. Sect. 11. 63 the portio dura, distributed in the substance of the mem- brana tympani * so as to excite tension in the fibres, in order that it may accommodate itself to the various in- flections of sound ; and by this means be rendered capable of transmitting- the most delicate vibrations. But this beautiful arrangement of the structure of the membrana tympani, assisted by the machinery of the ossicula and distinct muscles, under the controul and influence of Ihe minute fasciculi of the chorda tympani, is however, unavailable in rendering auditory perception accurate^ if the ceruminous tubular circle be destroyed. In cases of induration and relaxation of the mem- brana tympani, it has been proposed to apply a strong- solution of nitras argenti to the membrane, by means of a camel hair pencil ; but very bad effects of this application are already on record. I have lately seen several cases treated in this manner, and the effects were destruction of the sensibility of the parts, and of the ceruminous glands. Can that which destroys vitality, * The membrana tympani of the Balaena Mysticetus, furnishes a beautiful illustration of the distribution of reticulated nervous fasciculi, formed by branches of the Portio Dura. The large branches ramify on the white membranous sub- stance under the cuticle, and the minute ones terminate near the inner surface of the membrane, which renders it susceptible to the slightest undulatory piilsa- sations, and possessed also of power to accommodate itself agreeable to the wij/^ of the animal. 64 enter into the circulation of the parts, and promote heahhy action ? In parts possessing great depth of muscular substance, the application of caustics may sometimes be admissible ; but to a substance so thin and extended as the membrana tympani, and of such vital importance to the organ, the consequences resulting from the application of strong caustic lotions, must be fatal to the healthy action of the parts. The injection of pyrolignous acid, as mentioned in the Illustrations of Acoustic Surgery, is a preparation, that when assisted by the necessary medicines, will answer every useful purpose in changing the morbid into healthy action, and stimulating so as to produce the necessary degree of tension, consistent with the vitality of the mem-, brane and adjacent parts, When a person is exposed to boisterous weather, the volatilization of the cerumen takes place slowly, some- times only partially, and hence one reason why persons travelling in bad weather have to speak louder to each other in order to be heard, than when they are within a room of moderate temperature.* The halitus of volatilized cerumen, is therefore of the Vitmost consequence, to preserve the membrana tympani * Change of position, as well as the state of the atmosphere, will tend to prevent the pulsations of sound from being so distinctly heard, as when delivered in ai^ ^pa^rtment. Sec Appendix. • 65 from the effects of moisture or drought, produced by the state of the atmosphere, and also in stimulating* and promoting the healthy tension of the fibres of the mem- brane, and keeping it moist, so that the delicate pulsations and inflections of sound, may be transmitted to the in- ternal parts of the ear, more acutely than could otherwise have been done if the membrane were dry,* as will be shown by the following experiment. I procured a tin instrument similar in shape to that of an ear trumpet, but considerably larger, consisting of four pieces, which fitted neatly into each other. By this means I was enabled to apply a piece of bladder across the caliber of the tube, at the distance of three, six, or nine inches from the aural or small aperture, according to circumstances. The piece of bladder was intended to represent the membrana tympani, and was fixed neatly at about six inches from the small aperture. I then placed my watch on the table, at a little distance from me, and applied the instrument to my ear ; when I could hear the watch beating considerably louder than without the aid of the instrument. I removed the piece of dry bladder, and applied in its place another piece moistened in water. On applying the trumpet to * All parts of the human system, when in a healthy state, are more or less moist according to their desiguatiun, and perspirability. K 66 my ear, the beating of the watch became more audible and distinct than when the dry bladder was applied, at the same time the tones of the pulsations were con- siderably softened. In addition to the uses already mentioned, the cerumen may be considered as a regulator to modify the quantum of electric fluid, which may enter the meatus along with the condensed pulsations of sound.* In order to ascertain the effect which cerumen has on the electric fluid, I smeared the point of my finger with this secretion, taken recently from the ear of a boy of acute hearing, and then applied my finger to the prime conductor of a small electrical apparatus, and felt a slight sensation of the presence of the fluid, but perceived no sparks. On applying one of my other fingers on which there was no cerumen, I received several sharp pene- trating sparks emitting noise and light, as usual in such instances. My eldest pupil tried the same experiment with the same result. I continued to repeat the experiment several times, with my finger covered with cerumen, and once or twice * The atmosphere sometimes abounds so much with electric fluid, particularly in fine warm weather, that it has been supposed, by Mr, Murray, to be the means by which the aerial spider (Aranea Obstetrix) projects its filaments into the air. For an account of this interesting' and ingenious theory, see Experimenta,i Jtesearches in Natural History. By John Murray, F.S.A., &c. Glasgow, 1826. 67 saw ahd felt a few weak sparks ; but when my finger was deprived of the ceruminous coating-, and apphed to the instrument in that state, I received always a number of strong penetrating sparks, accompanied with crackling- noise, and light. It Would appear from these experiments, that the cerumen protected the internal parts of the organ, from the electric fluid that may be concentrated by the con- densation of the pulsations of sound ; that is to say, divested the pulsations of their intensity, and, perhaps, some other properties ; changing, or modifying* them, so that they may be assimulated to the galvanic fluid, so remarkably predominate, and assimulating to the ner- vous fibre, rendering it thereby more efficient and con- * Mr. Sturgeon, of Woolwich, has, by a number of ingenious experiments on Electric Discharge, ascertained that the quantity of aqueous fluid regulates the intensity of the shock. " I have," says that gentleman, " frequently discharged a jar through my own body, without any other inconvenience than a burning sensa- tion at the extremities of the fingers, and have ignited gunpowder in the same circuit. So modified is the electtic discharge, by being transmitted through aqueous conductors, that the effect of an intense charge oj" the most powerful battery may be reduced to almost any degree. I have discharged eight feet of charged surface (eight feet of lining, and eight of coating) through my own body, without feeling the least shock. But the burning sensation was very severe." Philosophical Magazine, Vol. LXVlI. Page 445. And hence may be accounted the effect which the ceruminous tubular circle has in regulating the intensity of the gaseous fluid, contained in the condensed pulsations of sound, especially when they proceed from large bodies that have the effect of causing violent concussion of the atmosphere. k2 68 genial to auditory sensation, than if the fluid had been admitted in its concentrated state. The cornea of the human eye is protected from the continued stimuli of rays of light and reflecting bodies, by the frequent action of the palpabrse washing the lachrymal fluid over its glassy surface; and by this means, its beautiful pellucid substance is preserved in all its transparent lustre. The auditory perception in the organ of hearing is also so frequently exercised, that without some provision to allay irritation, it would soon become callous, except to the impulse of strong pulsations of sound. It is, therefore, necessary to protect the internal parts of the ear from the effects of the condensation of the pul- sations of sound ; and for this purpose, the above modifi- cation takes place by means of the cerumen, in order to preserve that delicate perception necessary to the accurate and acute ear. In a paper which I wrote on the Comparative Anatomy of the Ear of the Squalus Canus, part of which appeared in the Edinburgh Philosophical Journal, January, 1826. In the Physiological department of that paper, after describing the arrangement of the nerves of the organ, 69 and the nervous circle formed, so as to receive and communicate the slightest vibration, I mentioned, " We may therefore presume from these circum- stances, that the sensation of hearing- is perfected by the existence of the electric fluid, modified according to the nature of the parts which it may enter, which in its tangible state displays the course and rapidity of vibra- tory motion. And that auditory sensation cannot exist, unless when the vibrations affect, and fill up the chasm so as to connect the extremities of the fasciculi forming the nervous circle; and hence may be the reason why the whole of the auditory apparatus and nerves assume a circular figure." " And this is farther confirmed, when we observe, that it is only the extremities of nerves that are endued with the particular sensation for which they are destined."* * The reason why I insert this theory as a, quotation from the above paper, is, that it was written in the latter end of 1825; and that excellent paper by Mr. C. Bell, on " The nervous circle which connects the voluntary muscles with the Brain" was read before the Royal Society, in January, 1826. My paper was read to several of my friends, particularly the Rev. Mr. Colquhoun and Mr. Goodwill, two gentlemen of whose discrimination, as well as general information, I entertain the highest opinion. The whole of my paper was designed to have been published in the Edinburgh Philosophical Journal, but owing to several circumstances, only one section was printed. I am preparing to publish a work on the Comparative Anatomy of the Organs of Vision and Hearing, illustrated with drawings of the most remarkable specimens of these organs in my possession. 70 The existence of the ceruminous tubular circle in its most perfect form, is also an excellent criterion of the state of the organ. For if the meatus, tympanum, or labyrinth be diseased, no healthy secretion of cerumen takes place, in the external tube of the ear affected. 1 am well aware, that Sir Astley Cooper, in his history of the case formerly mentioned, appears to have a con- trary opinion when he says, "The slight degree of deafness of which Mr. P. complained, was always greatly increased by his catching cold." So far the worthy Baronet is correct ; but when he adds, " an eflfect which seems to have arisen from the meatus being closed by an accumulation of the natural secretion of the ear^^^ I am very much disposed to question the accuracy of the statement, and more especially when I read the following continuation : " For it frequently happened to him, after he had been some time deaf from cold, that a large piece of hardened wax, during a fit of coughing, was forced from the ear by the air rushing from the mouth through the eustachian tube." Now, according to this account of Sir Astley's, it must either be taken for granted, that the hardened wax was the cause of the cold, for he adds that the cold was "an effect which seems to have arisen from the meatus being closed by an accumulation of the natural secretion of the ear." 71 Or else, that the cold caused " an accumulation of the natural secretion of the ear," in corroboration of which, he adds, " for it frequently happened to him after he had been some time deaf from cold, that a large piece of hardened wax during a fit of coughing- was forced from the ear, by the air rushing from the mouth through the eustachian tube." That is to say, that the cold produced an extraordinary secretion of cerumen, so much so, as to block up the meatus until the "fit of coughing forced it from the ear,'^ According to the observations which I have made on the natural consequences of cold, when affecting the ear, it acts always so as to suppress the secretion of the ceru- minous glands,* and therefore, no accumulation of cerumen can take place from that cause. I have, indeed, often observed in those who have had the mem- brana tympani injured or destroyed, and who in general bad purulent discharge from the meatus at the time, that when patients of this description caught cold, an accumu- lation of this purulent, or semi-purulent matter took place, became condensed, and frequently caused greater diminution of hearing than that which formerly existed. * I am happy to find, that the most celebrated authors who have written on this subject, are of the same opinion, particularly M. Du Verney, who, in his Treatise, when describing the effects of cold on this organ, adds, "For cold thickening this wax and rendering it more viscious, causes it to obstruct and stop up the excretory ducts of the glands, as it may be observed in other neighbouring glandular parts," 72 If the consequences of cold were to be an increase of the " natural secretion" of the meatus, then, the indication of cure in diminution of hearing, arising* from a deficiency of cerumen, would be to expose the patient so as to produce a cold. Now this mode of treatment, however plausibly it may be deduced from the statement of the case mentioned, would be absurd, to term it no worse. It should therefore be laid down as a rule in all cases, that cold diminishes the secretion of cerumen ; and also, that when the ceruminous tubular circle is perfect, no disease exists in the membrana tympani, or tympanum. In all instruments usually applied to the ear for the purpose of condensing and thereby increasing the strength of the pulsations of sound, it may be remarked, that if the diameter of the caliber of the part of the instrument placed in the concha be diminished, the power of the instrument is augmented.* A similar process takes place in the meatus, when the cerumen is secreted so as to form the tubular circle, which in the healthy subject, is from one-twentieth to nearly a quarter of a line in thickness, so that the cerumen causes a * This holds good only to a certain extent, for if the diameter be diminished so as to form a capillary aperture, the pulsations become so condensed as to pro- duce a hissing noise by the strong current of pulsations striking upon the mem- brana tympani in a continued stream, so that the undulatory motion of the pulsations are lost, and the membrane prevented from vibrating freely. 73 considerable diminution of the caliber of the contracting- meatus * and at the same time the auditory power of the tube is augmented, and produces an effect on the membrana tympani, in proportion as the length of the meatus, and the size and position of the auricle and concha, is to the diameter of the caliber of the tubular circle. •]• Hence the great danger to the sentient parts of the organ, or even the membrana tympani, from the use of an ear trumpet. For when the pulsations of sound enter the large recipient or external orifice of an ear trumpet, which is sometimes five or six inches in diameter, and are propelled inwards, the sides of the tube prevent dis- persion, and as the instrument contracts in caliber, so the pulsations are gradually condensed, and produce an effect on various parts of the organ, in proportion as the length of the tube and its diameter at the mouth, is to the small or aural aperture. * The auditory tube, as formerly mentioned, is of a conical and partially wind- ing figure, the diameter of the interior parts near the depressional curve, in the well formed meatus, being in proportion to that of the expansion of the osseous aperture, at its junction with the cartilaginous part of the meatus, as two and a half is to three and a half in the length of four. — See Appendix, Table I. t The degree of susceptibility in the Portio Mollis, (and perhaps that of the whole nervous system of the individual,) must also be taken into account in forming a proportional estimate of the effects produced from the relative figure of the parts. L 74 Although an auricle were twenty-three or twenty-five lines in length, yet from its angle of attachment it would scarcely occupy one-third of that space in breadth, con- sequently, the recipient orifice of an ear-trumpet, if six inches in diameter, would be capable of retaining and conveying to the membrana tympani upwards of ten times the quantum of pulsations of sound, that a mode- rate sized auricle could possibly retain ; and which in its condensed state must ultimately injure and destroy the percipient qualities of the sentient parts of the organ. The caliber of the meatus in the well formed ear, is generally in proportion to the size of the auricle, and depth and size of the concha, but when the tube is either too large,* or too small, f the hearing is diminished in proportion to the departure from the healthy standard. In the Appendix is a table J taken from the measurement of one hundred living individuals, and which may serve as a criterion to judge how far the size of the parts may assist in regulating the diagnosis of any attempt to effect a lasting cure in cases of diminution of hearing. The consequences arising from the disease M. Permi- nutus, II is sometimes more easily remedied than that of * M. Peramplus. f M. Perminutus. % Table IV. see Appendix. II I have met with several cases of diminution of hearing in elderly persons, particularly females, arising from the auricles being bound down on the head ; and the cartilaginous parts of the auricle being pressed forwards by the bandage, 75 M. Peramplus^ especially if the diminution of the caliber of the meatus be occasioned by tumidity of the integu- ments. When the caliber of the meatus is contracted from the above cause, it may be considerably enlarged by introducing elastic tubes or short bougies made of catgut into the meatus, and afterwards slightly moistened with tepid water. The tube or bougie swelling by means of the moisture, causes pressure, and consequently absorption of the parts takes place, which enlarges the meatus in a slow gradual manner. Considerable tact will be necessary to prevent absorption of the ceruminous glands, or ulcera- tion of the parts, which occurs invariably if the pressure be so great as to cause pain and head-ache. On the first appearance of these disagreeable symp- toms, the tube or bougie must be withdrawn, and the case treated according to the directions mentioned in Injlammatio Supurata.^ The secretion of the cerumen, is considerably affected by the size of the tube, especially if it be much above that of the usual standard, where the atmosphere is admitted gradually contract the horizontal diameter, and ultimately block up or close the meatus. This species of diminution of hearing may be termed Impedimentnm Pressures Senilis, * For a particular account of the mode of treatment, see Illustrations of Acoustic Surgery. l2 76 in so large a volume, that the cold prevents the formation of the halitus, or even the secretion of the cerumen, and the membrana tympani being- partially unprotected, soon loses its delicate tone. The ceruminous glands become at first inflammed, afterwards enlarged, followed some- times by ulceration, but more frequently they are par- tially shrivelled, the tube becomes therefore gradually dry, and the integuments callous * Great diminution of hearing in the adult, and deafness in the aged, is the consequence of this species of malformation. In a case of M. Peramplus which came under my care, (patient seventy years of age,) where the tube was completely dry, and measured seven lines and a half in the longitudinal diameter, attended with considerable dimi- nution of hearing ; I applied a thick coating of artificial cerumen, so as to diminish the caliber of the meatus, and form a tubular circle. About fifteen minutes afterwards, the patient could hear when addressed in an ordinary tone of voice. The mechanical properties of the application, forming an extremely thick tubular circle, and thereby diminish- * Several cases of M, Peramplus came under my care, -where the caliber of the meatxis measured from six to eight lines in diameter. The inside of the meatus was completely destitute of the ceruminous tubular circle, being dry and shrivelled ; and even the mouths of the ducts of the ceruminous glands could not be dis- covered. The diminution of hearing was of course very great. 77 ing* the caliber of the meatus, assisted by the stimulating qualities of the preparation, and the pulsations of sound beino- condensed and transmitted to the membrana tympani with nearly equal power to that of the well formed meatus, succeeded in restoring the hearing of the patient. But the restoration of hearing lasted no longer than the continuance of the form and existence of the medical properties of the artificial tubular circle, which was renewed for several times with the same result.* Several very important criteria are to be found in the shape and size of the auricle, especially in the angle which it forms with the cranium, and also in the size and depth of the concha, which may assist to determine the prognosis in cases of diminution of hearing when the symptoms are obscure. As the figure and aspect of the auricle have consider- able effect in augmenting or diminishing the strength or condensation of undulatory pulsations, so they afford also excellent diagnostic symptoms to guide the practitioner in his mode of treatment of the particular species of disease which may affect the hearing of the patient, and * The meatus might also be contracted by means of a small tube smeared over with cerumen, and fashioned so as to fit neatly into the tube. 78 may, agreeable to Table IV., be reduced to the follow- ing axioms, viz. Axiom I. — If the concha be large and deep, the upper part of the helix rather overhanging, the scapha not pro- truding, the lobe inclining diagonally forwards, and the angle of attachment* from twenty-five to forty-five degrees ; the auricle is then formed to retain, concentrate, and convey into the meatus, the necessary quantum of undulatory pulsations requisite to excite acute auditory perception. J- Axiom II. — If the concha be small and shallow, and the angle of attachment of the auricle be nearly forty degrees ; this angle, formed by the auricle and cranium, compensates for the deficiency of that important cavity, by the quantum of pulsations which the auricle, by its position,, conducts into the meatus. Axiom III. — If the angle of attachment be small, and the concha large and deep, the capacity of this cavity, compensates for the deficiency of the angle of attach- ment. * The angle of attachment is found by applying a quadrant to the parts of the head immediately in contact with, and in front of the auricle. t In the female auricle, when well formed, the parts are in general more elegant than in the male, and the length greater in proportion to the breadth. In the 79 Axiom IV. — But if the concha be small and shallow, and the angle of attachment under fifteen degrees, the hearing' is rarely, if ever acute, especially in middle aged persons.* Axiom V. — And if to these imperfections, the meatus be small and circular, it adds considerably to the defective formation of the external, or recipient parts of the organ. •]• Axiom VI. — And if to any of these imperfections of the auricle, the meatus be large and circular, and the diameter six, seven, or eight lines, the person is gene- rally affected with diminution of hearing, which is in- creased with age. From these axioms may be deduced the propriety of paying attention to the head dress of children, as well as to those of aged persons ; in order that the auricle may become strengthened so as to retain its shape and position in the angle of attachment most favourable to receive the pulsations of sound. above axiom, it is taken for granted, that the ceruminous tubular circle is perfect, the intermediate and internal parts of the organ well formed, healthy, and possessed of the necessary susceptibility requisite to acute perception of sounds. * See Table IV. t See page seventy-two of this work, and particularly the note appended to that passage. 80 If the angle of attachment of the auricle of a child be small, it can easily be increased by applying* a pad and bandage, and continuing the same until the auricle assume a permanent position agreeable to the angle of attachment required * Females of all ages ought to be particularly careful in the form of their head-dress, so that it may not inter- fere with, or bind the auricle flat to the head, as the con- tinuance of this kind of pressure, will, sooner or later, cause the cartilage of the auricle to contract the horizontal diameter of the meatus, and ultimately block it up. ■]• That the angle of attachment of the auricle to the cranium, has a very great effect in diminishing or aug- menting the strength of the undulatory pulsations of sound, even when the ceruminous tubular circle is fully formed, may be illustrated by the following case. * This can be more readily accomplished with the male child than with the female, by means of the hat usually worn; and which ought always to be placed on the child's head, so as to cause the upper part of the auricle to overhang the concha. Nurses ought to be careful never to place the auricles within the hat, because this manner of wearing it, will ultimately tend to flatten the auricle, and decrease the angle of attachment. t The obstruction caused by means of the cartilage of the auricle blocking up the meatus, forms, as has been already mentioned, the species Impedimentum Pressure Senilis. This species of obstruction is never found but in aged persons, and more frequently in female than in male patients, 81 " Mr. E — e, aged thirty-nine years, returning- home late in the evening, fell on the handle of a pump, which being square and made of iron, the edge of it cut into the auricle and almost severed the greatest part of it from his head. Considerable hemorrhage took place, but, with the assistance of his family, he succeeded in stopping it, and went immediately to bed. I was called in next morning-, and found the meatus blocked up with coagulated blood, which was removed with difficulty, on account of the Pili Auricularis being involved in the coagulum. The auricle was divided through the integuments and cartilage, and the detached portion connected by a small slip of the helix, rather more than the breadth of a line. I washed the parts with tepid milk and water, brought the edges of the wound together, and passed one suture through the integuments, near the inferior part of the scapha, and another rather below the upper part of the concha. And, in order to keep the parts in apposition, particularly the cartilage, I applied a suture through the integuments on the back of the auricle, next to the cranium, equi-distant from the sutures on the other side of the auricle, and strengthened the parts with slips of adhesive plaster. I then formed a pad, and placed it so as to retain the auricle at an angle of nearly forty-five degrees from the cranium, and secured the whole in the M 82 manner described in the 'Illustrations of Acoustic Surgery/* The patient did not complain of much pain, and as he was of temperate habits, and confined himself to his room ; the parts were healed by the first intention in a few days. The cicatrice could scarcely be discovered, except on minute inspection. But the most satisfactory part in the history of the case was, that the patient could afterwards hear better with this ear than the other, which forms an angie of attachment of about ten degrees with the cranium. "I* This case illustrates the great importance of the angle formed by the auricle with the cranium, in rendering- the hearing acute. But the following history of a case so hopeless as to have discouraged several eminent Physicians as well as Surgeons from attempting a cure, is still more conclusive than the above, in showing the effect of the angle formed by the auricle and cranium. A country gentleman about fifty-seven years of age, applied to me under the following circumstances. " Has had great diminution of hearing in the left, and almost deaf of the right ear, upwards of twenty years ; * For a description of the Auricular Pad and Bandage, see Illustrations of Acoustic Surgery, chap. IV. page 29, and plate V. ■\- When he informed me of his accession of acuteness of hearing, I proposed to cut off the flat auricle, or at least make an incision, and endeavour to heal it so as to form a corresponding angle with the other ; but to this he would not consent. 83 and at present can scarcely hear a word spoken, unless the person speaking shout very loud. Meatus dry and large. Concha very shallow. Auricle forming an angle of sixteen degrees with the lateral parts of the cranium.* Has had advice, and been under the care of several medical gentlemen, without experiencing any ameliora- tion of his complaint. A practitioner under whose care he had once placed himself, poured into the meatus of the right ear a fluid, the nature of which he (the patient) did not know ; but it caused such intolerable pain as almost to distract him; and this ear has always been worse than the other, since that period. ''-j* On the formation of the artificial tubular circle, the hearing was considerably improved in his left ear ; but as he lived upwards of seventy miles from Hull, and business requiring his immediate return, I resolved to try some other mode, in addition to the application of the artificial tubular circle. From the very small angle of attachment of both auricles, being only sixteen degrees, I was led to believe that by applying a pad so as to extend the natural angle * The size and dimensions of the auricle and meatus of this patient, are given in Table IV. No. 13. t Taken from the notes of the case. 84 of the auricles to forty-five degrees, the hearing might be considerably improved. I made tvro temporary pads, and the patient vs^earing- glasses, I was thereby easily furnished with the means by which the pads could be secured in the position re- quired. I fastened a pad to the end of each of the handles of his glasses, and in the space of five minutes after they were adjusted, he could hear me speaking to him in an ordinary tone of voice. It may be remarked, that whenever the horizontal diameter of the caliber of the meatus exceeds three lines, diminution of hearing invariably takes place ; unless there be peculiar advantages in the size of the auricle, its angle of attachment, capacity, or depth of the concha. In Table IV. there are only six persons in the hundred, whose meatus measures three lines horizontally ; and of that number only one has acute hearing, viz. No. 62. But this extraordinary circumstance in No. 62, is chiefly owing to the individual being strong and muscular, and of active habits, the auricle rather above the usual size, the concha very deep, and the cranium very large. No. 76. has the meatus large, but as the auricle is of a tolerable size, the greater part of it at an angle of thirty degrees, and the lobe at an angle of fifty-two 85 degrees, and no unhealthy symptoms in the nervous system, the hearing is therefore good. If the angle of attachment be under twenty degrees, the hearing will be diminished, unless compensated by a large and deep concha ; because a sufficient quantum of the pulsations of sound cannot be conveyed to the membrana tympani, so as to form acute vibration of that membrane, if the auricle be small, and attached to the cranium in that position. As the angle of attachment exceeds twenty degrees, and approaches towards forty- five degrees, so the hearing becomes more and more acute, according to its grade of approximation. If the angle of attachment be forty degrees, the hearing is always acute ; unless the meatus be very large, and the concha extremely small and shallow, or the intermediate, or internal parts of the ear injured. The angle of forty-five degrees, appears to be the best at which the auricle can be placed, so as to receive, retain and convey the greatest quantum of the pulsations of sound to the membrana tympani. In several parts of the concha, but particularly around and in the entrance of the meatus, are numerous small ducts, visible to the naked eye. These are the ducts of the sabaceous glands. The secretion is limpid and tasteless, and very plentiful in some individuals. I have 86 taken out of the concha of a healthy person, upwards of one-fifteenth part of a dram.* There is a remarkable case related by Dr. Barnes, of a vicarious menstruation which took place repeatedly from the ear of a lady, of a liquid which had neither taste nor smell.* The history of this case agrees so exactly with my own observations on the secretion of the sabaceous glands in the auricle, that I have no doubt the discharge mentioned might be emitted from the ducts of these glands, in the entrance of the meatus and concha. In the case mentioned, it is stated that the discharge " was colourless, and had neither taste nor smell. The ear was dry in the interval." Now as the remarks by Dr. Barnes, on this extraordinary case, are so appropriate and valuable, it is therefore to be regretted, that he has not given a more explicit and minute account of the state of the concha, but particularly of the meatus, especially when it was the seat of disease, according to his account in the above paper. * The measurement of the auricle of this individual, is given in Table IV. No. 29. And I may add that he is of remarkable temperate habits and healthy constitution ; but rather inclined to corpulency. * " Case of Vicarious Menstruation, -with, singular discharge from the ear, with remarks. By Thomas Barnes, M.D. Physician to the Fever Hospital and Public Dispensary, Carlisle, &c. Communicated by Benjamin Bell, Esq. Edinburgh." Edinburgh Journal of Medical Science, October, 182C. 87 In a note by the learned Editor of the above Journal, forming- a very elaborate critique on Dr. Barnes' paper, a case is given as an illustration of the discharge in ques- tion, and vi^hich was laid before the public by Dr. Russel, in his inaugural dissertation De Otorrhoea. After re- lating the preliminary history of the case, (of a girl,) the Editor mentions, that " of a sudden an eruption, to vrhich she had never been subject, broke out about, but not in the ear, with a copious discharge (this we saw many times a day) from the meatus, of a pellucid colourless, nodorous fluid, but so acrid that it excited pustules and scabs over all the parts of the cheek and neck upon which it flowed.'^ From this description, it may at once be recognized as Injiammatio Suppurata, induced by bathing (as the history of the case relates,) in the sea at New- haven. I have had several cases of the above species of inflammation of the meatus under my care ; but the discharge in my patients, was in general slightly tinged, and this partial discolouration proceeded from the patients having been several days, sometimes weeks or months affected with this complaint, before their ap- plication to me for relief. Whereas in the case mentioned in the note, the learned Editor having the patient already under his superintendence, prior to the appearance of the discharge, was by that means enabled to see the very beginning of the primary stage of the disease. 88 The use of the secretion of the sabaceous glands may be partially inferred by analogy. As bodies when dry and hot, have more or less the power of attracting the electric fluid, especially when they are pointed and projecting ; so there might be some danger of the auricle, (by means of its figure and position,) attracting the gaseous fluid, if the parts, when evolving caloric, continued in a dry state. The secretion of the sabaceous glands, which is limpid and tasteless, may, when the individual is heated by active exertion, tend to prevent the electric fluid becom- ing prejudicial to the hearing ; or at least modifying its influence, or lessening the attraction of the heated and projecting auricle, and of course the accumulation of that fluid in a concentrated state.* By all the accounts which I have seen of those persons who have suffered by the fatal effects of the electric fluid, * In a very ingenious paper by Mr. Sturg'eon, of Woolwich; on the Ignition of Gunpowder by the Electric Discharge, and which has been mentioned in another part of this work, it appears, that when the conductor which was made of twine, and well soaked in water when used, ignition did not take place so readily as when the twine was but partially moistened. These experiments are valuable, inasmuch, as the arrangements by which the results were obtained, are greatly facilitated by Mr. Sturgeon's communication ; but particularly that part which relates to the modification of the intensity of the discharge which takes place by means of the conductors being moistened with water. See Journal of Science, Vol. XXII. Page 200, and Phil. Mag. Vol. LXVII. These experiments were also tried by Mr. Leuthwaite, of Rotherhithe, and are recorded in the same Journal, Vol. XI. Page 393. 89 the individuals have been of a dry temperament, not given to perspiration, at least the skin has been dry at the time the accident happened, and from their situation in respect to the surrounding space, become a point of attraction to the concentrated fluid. When man is heated by active exertion, the perspira- tion is more abundant on the forehead than on any other projecting part of the frame, and this may be the more necessary, in order to relieve the parts, and at the same time shield the source of vital, intellectual and physical power, and render it repulsive to the electric fluid, whether diffused or condensed in the surrounding atmosphere. I have thus given a brief account of the physiology of the recipient parts of the organ of hearing, and endea- voured to impress on the mind of the practitioner, the importance of the shape and size of the auricle, and the angle formed by its attachment to the cranium; and also, the figure, size and position of the meatus, but more particularly that of the ceruminous tubular circle, in rendering the hearing accurate and acute. • The cerumen is so absolutely necessary in preserving- accurate vibrations in the membrana tympani, and con- sequently acute sensation, that without this peculiar 90 secretion, all the beautiful arrangement of structure in this membrane and machinery of the ossicula, and even the sentient qualities and percipient powers of the portio mollis itself, would soon become alike insensible to the shrill, sweet, or harsh pulsations of sound, their modifications or inflexions, whether proceeding from the cultivated tones of the human voice, or the more rugged species of animated nature.* From these views of the subject, we are led to admire the beautiful simplicity of the various contrivances adapted to render every part of the organ efficient, and, in none more than in the secretion of cerumen, in which is displayed the greatest design united with mechanical arrangement : and, should the economy of this organ appear to the philosophical mind, so com- prehensive and grand, as to soar with sublimity above all human inventions ; let it be remembered, that even when arrayed in all the pride of symmetry and ex- quisite organization, it conveys only a faint idea of Infinite Wisdom. * There is no doubt that a corresponding degree of symmetrical proportion in the tympanum, mastoid cells, eustachian tube, and labyrinth, as well as in the susceptibility of the organization of the portio mollis, is also requisite to form an acute ear ; but as the limits of this Treatise do not include these parts of the organ, the discussion of their individual and peculiar qualities shall be reserved as a subject for a future publication. APPENDIX, CONTAINING VARIOUS TABLES AND FORMULAE, WITH PHYSIOLOGICAL AND ANATOMICAL REMARKS ON THE OF THE ORGAN OF HEARING IN SEVERAL ANIMALS. PROEM. It is generally allowed that comparative anatomy illustrates the physiology of the human body better than the most elabo- rate definition, especially if there be a variety of figure and position in the parts to be investigated. I have, therefore, added an Appendix, containing such Tables and Remarks as may tend to elucidate the various theories introduced into this publication. It may, perhaps, be necessary to premise, that in the following Tables of the dimensions of the meatus, the superior line extends from the superior part of the external orifice to the membrana tym- paui, and the inferior line begins at the inferior part of the ex- ternal orifice, and terminates in the interior, or tympanal extremity of the tube. The depressional curve commences nearly opposite to the con- nexion of the superior line vnth the membrana tympani, at an angle formed in the tube, and which is more conspicuous in some individuals than in others ; and includes all that part of the meatus between this angle and the membrana tympani. The longitudinal and horizontal diameters of the caliber of the auditory tube in preparations, as well as in those of the living human subject, are designated agreeable to the erect position of man; and, in specimens of comparative anatomy, they are given in conformity to the natural position of the animal. TABLE L DIMENSIONS OF THE MEATUS AUDITORIUS EXTERNUS OF THE JHumatt ^uf)iutf (CfflEFLY OF THE OSSEOUS CALIBER,) TAKEN FROM PREPARATIONS IN THE POSSESSION OF THE AUTHOR. TABLE I. Number or character of the Description. Length of the Meatus. Diameter of the Caliber. Preparation. • Sup. line. 1 Inf. line. loep. Cun-e. Long. Horiz. Prep. 1 Preparation, a longitudinal section of the left tube ; male adult. Do, with the integuments of the right tube injected and dried ; male adult. 10 8 1 10 _i_40_ 10 _3_4Jl_ 10 10 P. 2. _6j_o_ 10 8 1 10 tVA A very fine specimen of the parts, the longitudinal diameter measures large: depressional curve more acute- ly marked than usual. Oss. _i_3_0_ 10 10 _3_0_0_ 10 AVo P. 29. Diameter at the Dep. C. 100 C. 1. Craniae of two male Esquimaux, dug up on the West Coast of Davis' Straits. Oss. 4 3 10 t¥A C. 2. 4 2 10 tVVo C.3. Cranium of Booth, executed at York, for murder. Oss. 6 3 10 3_7 Too^o' C.4. Two male Craniae, of which I tVoV 3 10 C.5. dissection. Oss. tVVo 3 0_7 10 P. 16. Female, preparation dried. 5 10 t¥A Z. Male Cranium. Oss. 6.S-8.-_5 10 3 6 10 y. Adult male Cranium. Oss. 4_7 10 S.fi_4.-Ji 10 X. Adult male Cranium. Oss. 10 3J.i)l5 10 Preparation with the integuments, injected and dried. tVoV Too'o" Male, ten years of age. tVoV iU^ Female, six years of age. 10 To'0'0" 22. Female, one year old. 1'"0 0"'ff AAAl? 10 21. Male, sixteen years of age. tfo^ 300 10 Male, two and a half years of age integuments dried. To'0'0 2 0-1 1 17. Subject six years of age. 3 0.3 TTT'oo^ 940 10 18. Subject five years of age. 3 3 10 S.A7.-& 1 0^00^ The above measurements are taken on a scale of 1000 parts to an inch. 95 In the plate given by Soemmering',* of the caliber of the meatus, neither the depressional curve nor the recli- nation of the membrana tympani is vrell defined. There are certainly great varieties in the size and figure of the caliber ; but I have often observed, that all those indi- viduals in whom the angle described by the beginning of the depressional curve, was slightly marked, the hearing was never so acute as when it was formed of a strong angular figure, particularly if the ceruminous tubular circle were imperfect. In Plate I. I have given a sketch of a longitudinal section of the caliber of the meatus, with the membrana tympani attached to the mal- leus, a preparation distinguished for its symmetry and beauty ; and in Plate II. a sketch of a longitudinal section of the meatus of an extremely well formed ear, with the parts adjoining-. Soenamering, in his beautiful plates of this organ, has delineated three divisions of the meatus, without ascrib- ing any use to these divisions of the tube , j* Dr. Kirby, the learned editor of Monroe's Anatomy of the Human Bones, has added a supplement to his last * Samuelis Thomas Soemmerring, Icones, Organi Auditus Humani. Francofurti ad Moneum, 1807. Y " Curvatura eius prima seu major." " Curvatura secunda, sive minor." " Curvatura tertia, minima." Tabula Quarta. 96 edition of that work, containing a description of the structure of the internal ear, where he describes the meatus " to run inwards in a curved direction, first rising coronad and glabeliad, and then turning hasilad. * Saunders, in his treatise, describes the meatus as winding. " It is first turned upwards, then downwards, and is again slightly bent near its termination." •]• Neither of these authors assign any reason why the hearing can be assisted by this irregular form of the caliber of the tube. In another part of this work, I have ventured to form a theory on the utility of the depressional curve, to which, I beg leave to refer the reader. * Anatomy of the Human Bones and Nerv€s, page 287. Edinburgh, 1820. t Treatise on the Anatomy of the Human Ear, by J, C. Saunders, page 3. ■ London, 1806, TABLE 11. DIMENSIONS OF THE MEATUS AUDITORIUS EXTERNUS IN (CHIEFLY OF THE OSSEOUS CALIBER,) TAKEN FROM PREPARATIONS IN THE POSSESSION OF THE AUTHOR. TABLE II. Number or character of the Description. Length of the Meatus. Diameter of the Caliber. Preparation. Sup. line. 1 Inf. line. loep. Curve. Long. Horiz. P. s. Preparation (in spirits of wine) of part of the meatus of a young- whale (Balaena Mysticetus.) The tube is surrounded by a semi-car- tilaginous substance, from three to four lines in thickness. Measure- ment taken at about three inches from the merabrana tympani. J.J.J.i5 I U 1 2 4.5 10 p. s. A. In a dissection of a foetus of the B. Mysticetus (subject 13 inches 3 lines long) I was unable to ascer- tain the orifice of the meatus, or even the tube itself, after a very careful dissection. Prep, of the external orifice of the meatus of the B. Mysticetus, subject forty-tliree feet in length : aperture in the quiescent state, colapsed, and forming a long oval. D. A. Hi-t' A. Section of the meatus of the Sea Unicorn, or Narwal, (Mono- don Monoceros.) Section of the meatus of the M. Monoceros, at tlie expansion near the membrana tympani. Section of the meatus of the M. Monoceros, about half an inch above the m.embrana tympani. 160.5 1000 1 fi o-s 10 D. B. 10 tVo^o D. B. 10 ToVo- 116 D. Prep, of the right ear of the Sea Horse, or Walrus, (TrichecusRos- marus.) The organ is finely se- cured from violence by the Mastoid Process, a huge massive body of solid bone, upwards of an inch in thickness. ItVVo •'^T'oo'o' tVA 1000 1000 Meatus of the Dog-Pish (Squa- lus Canus) subject three feet in length. The tube is retained in its acute angular position by strong tendinous fibres, so remarkably fine and pellucid, as scarcely to be dis- tinguished amid the transparent gelatinous substance, by which the meatus is surrounded. Measure- ments taken a few hours after the animal was killed. 2 OJIii) 10 To'T) o" At the orifice. P. S. 1 4-3 1000 tWo" Inside of the Cuticle. _A2._ 1000 _J.9._ 10 C. Green Monkey (Simla Sabaea) The meatus is formed chiefly of cartilage, so that the osseous part of the tube has a similar appear- ance to that of the human foetus. Oss. nu _2_1_0 10 D. P. Elephant (Elaphas Maxiraas.) This specimen has received con- siderable damage in the cellular substance of the cranium, so that there is the greatest probability that the osseous tube of the meatus is not complete. Oss. • 1 -J? 3 .5 ■■■10 r-oVo The above measurements are taken on a scale of 1000 parts to an inch. TABLE II. CONTINUED. Number or character Description. Length of the Meatus. Diameter of the Caliber. Preparution. Sup. hne. Inf. line. Dep. Curve. Long. j Horiz. D. P. Prep, of a Seal (Plioca Vitu- lina.) Section of the meatus lon- gitudinally. 72 1 10 1 110 ■■■1000 _4-3_Q_ 10 1 I f> 10 _2_7_S 10 Cran. Cranium of a Seal, (P.Vitulina,) integuments dried. 1 i .5 10 1 4 S 10 128 Prep, of a Seal, (P. Vitulina,) integuments more full than the above. 10 1 1 .5 10 121 Prep, of the ear of a Seal, (P. Cristata.) Oss. 3 .5 10 0.. _4_8_1_ 1 u External orifice of the meatus of a living Seal (P. Vitulina) ob- long figure. 1 ■ ,5 10 2_ surrounded, so as to prevent aerial circulation in the tube, and render the vibrations of the membrana tympani imperfect ; in the same manner that obesity in the human subject, causes a considerable diminution of hearing, if the eustachian tube be obstructed by pressure from the swollen glands and increased muscular substance. Hence, one reason why whales, when very fat, are more easily approached and captured than those of less bulk. In the Balsena Mysticetus, the caliber of the meatus forms the four thousand three hundred and sixtieth part of the whole length of the animal, allowing it to be forty-five feet. 103 The meatus auditorius externus in most animals conducts the pulsations of sound to the membrana tym- pani, and are thence transmitted by that membrane to the sentient parts of the organ, in order that perception of sound may take place : but in the Balsena Mysticetus, the pulsations of sound are conducted by the eustachian tube into the tympanum, and proceed through this cavity to the membrana tympani ; at the same time, the meatus performs the office of the eustachian tube by facilitating the vibratory action of the membrane ; and hence the cause of the external convexity of the membrana tym- pani in the whale, the reverse of that which is seen in most animals. MEATUS MONODON MONOCEROS. The meatus of the Narwal (Monodon MonocerosJ is situated similar to that of the B. Mystieetus ; but considerably larger in caliber than that of the whale. I am at present unable to determine the exact size of the external orifice of the meatus, having no speci- mens of that aperture in my collection ; * but if it may be allowed to judge by analogy, it should be rather smaller than that of the seal. The tube of the meatus is chiefly formed of strong ligamentous substance, varying from half a line, to one line in thickness ; except a small circular portion of peculiarly hard osseous substance, (a continuance of the parietes of the tympanum,) whence the membrana tympani derives its origin, and which measures in diameter from -j4/-5_ to ^YoV P^i"ts of an inch.-j- * I have however, upwards of twenty specimens of various parts, and also several preparations of the organ in situ. t The -whole of the osseous part of the organ is composed of extremely dense particles, similar to that of the petrous portion in the human ear. P 106 The greater part of this hard petrous substance describes a novel kind of circular arch, rising and bending inwards to the central line of the meatus, then curling downwards and rather outwards and upwards, somewhat similar to the spiral lines frequently seen carved on wooden work in old churches. This peculiar curvature of the osseous portion of the auditory tube, may serve the same purpose as the depressional curve in other animals. To the edge of this curved process of the bone, the tendinous portion of the tube is attached, and which necessarily causes the tendinous portion to assume a trumpet-like appearance. The caliber of the tendinous tube, contracts rapidly to jV^V pa^i*ts of an inch, and afterwards in the space of ten lines from its attachment to the osseous portion of the tube, enlarges gradually to T^o^i parts of an inch. The whole of the auditory tube is lined with a reflection of the cuticle. It ought to be remarked, that as the membrana tym- pani of the narwal is concave externally, and its attach- ment to the malleus deviates considerably from that of the while, or even terrestrial animals ; so, the use of the meatus in the narwal, must therefore necessarily vary, in proportion to the deviation in size and figure of its membrana tympani, from that of the B. Mysticetus. MEATUS AUDITORIUS EXTERNUS SQUALUS CANUS. The orifice of the meatus auditorius exteraus in this species of the shark, opens on the coronal surface of the head, is small, but capable of admitting a bristle. After passing through the cuticle, the caliber of the meatus enlarges to above twice the size of the external opening, and runs forwards and downwards, and rather inwards, until it forms an acute angle by turning backwards, downwards, and rather outwards, when it reaches an aperture in the cranium, through which it passes into the vestibule. At the acute angle of the meatus, the inferior and posterior portion of the tube is carried almost horizontally forwards, until it arrives near the superior and anterior portion, where it contracts to an extremely small aper- ture, situated on the outer edge of the duplicate of the posterior and inferior portion of the tube. This small aperture or capillary duct, makes a small semi-circular turn outwards, downwards, and backwards over the edge of the reflected portion, and then enlarges in proportion to the cavity above. p2 108 The posterior part of the tube being also reflected backwards, and closely united, and in contact with the horizontal parts immediately above, while the anterior portion by means of the angle formed, becomes the infe- rior, and enlarges along with the other parts of the tube to the size mentioned ; and in this manner, a valvular membrane is formed by a duplicate of the posterior parts of the tube, and, which I have termed the Membrana Vestibuli. The meatus, in its descent from this valvular mem- brane towards the vestibule, forms an oblong globular expansion, and then contracting into a small aperture, arrives at the foramen in the cartilaginous cranium, to the edges of which it is firmly attached, and passing- do wnwards, joins the great sac of the vestibuli. The parietes of the tube immediately below this globular expansion, is strong and muscular, and forms a sphincter of considerable power.* The tube of the meatus is secured in its position by numerous tendinous fibres, which ramify in all direc- * It must at the same time be allowed that, if the scalpel be used freely, these adhesions may be cut and the tube forcibly extended as if it were merely a duct ; but the above description is given, agreeable to the appearance of the parts in situ, and the result of nearly one hundred dissections of the organ of hearing in this species, (S. Canus) in its most perfect and healthy state. By means of the proximity of this place (Hull) to the sea, I could sometimes procure any number of the heads of these animals, at comparatively little ex- pense, so that there vi'ere no obstacles to prevent the dissection at such times as were most convenient. 109 tions; and are extremely minute in size, but of great strength, and nearly transparent. The auditory tubes,* by means of the angular figure which they describe in their descent to the vestibule, occupy a considerable portion of the large depression situated in the coronal and posterior parts of the cranium. The remaining space is filled with transparent gelatinous substance, the tendinous fibres, and two muscles, one of which is attached to each tube. These muscles take their origin from the edge of the cavity or depression in the cranium, and above the anterior margin of the foramen labyrinthi, and run obliquely in- w'ards, forwards and downwards, and are inserted in the angle of the reflected portion, which forms the membrana vestibuli. The muscles are of a beautiful white colour, and easily seen when the skin is carefully dissected back- wards, from about half an inch anterior to the orifice. Dr. Weber, in his delineations of the ears of fishes, describes similar muscles in the Rai(B Miralaii, and also in the JR. Torpedinis, but does not mention their ex- istence in the S. Canus ; it may, therefore be pre- sumed, that this is the first time these muscles have been demonstrated in the dog fish.j* * Termed by Dr. Weber, Sinus Auditorlus Externus. t De Aure et Auditu Hominis et Animalium. Pars I. De Aure Animalium no I am fully aware of the formidable and respectable list of authors who maintain that there is no external meatus in the shark. Cuvier and Scarpa, who have rendered themselves illustrious in the annals of phi- losophy, for scientific investigation, as well as Bell and Macartney, deny the existence of the auditory tube in the Squalus.* On the other side of the question, our no less cele- brated countrymen, Monroe and Hunter, have both laid claim to the merit of discovering the external opening of the meatus. But neither the one nor the other mention the existence of the valvular membrana Aquatilium. Auctore Ernesto Henrica Webero. Phil, et Med. Doct. in Universitate Lit. Lips. Prof. Anat. Comp. Extraord. Lipsiae, 1820. * " To these authorities we may add that of Scarpa, who asserts in the most positive manner, that there is no opening of the ear in the flat or round cartila* ginous fishes ; he supposes that the foramina which Dr. Monroe discovered, were the openings of some of the ducts containing gelatine which are found in this situation ; he even treats Dr. Monroe's account with derision, and considers it absurd to suppose that there should be a communication between the external element, and the immediate seat of the sense of hearing. Scarpa, in denying an external opening, admits the existence of a conduit from the integuments into the vestibu- lum, or sac, containing the amylaceous substance. In this Cuvier agrees with him, and we add, we have frequently and carefully dissected the organ of hearing in the Ray and Shark genera, but have never been able to discover the opening men- tioned by Monroe and Hunter. What we have observed agrees almost exactly with the description given by Scarpa." Rees' C yclopasdia.^Fish. — Organ of hearing. Supposed to be written by Macartney and Lawrence. " We may conclude then, that fishes have no external opening like terrestrial B."— J5«i/V Anatomy, Vol, III. page 133, London 1823. Ill vestibuli, or that of the muscle, or the structure of the tube itself, by means of which, the surrounding element is separated from the contents of the great sac. The muscular structure of the tube of the meatus, will pre- vent the admission of the surrounding fluid, independent of the action of the muscle ; and this may perhaps be one reason why I have found such great diversity in the size of the membrana vestibuli, and capillary duct. Dr. Weber in his Treatise (already mentioned) on the Ears of Cartilaginous Fishes, gives a sketch of the muscles of the external meatus, or as he terms it, " Sinus auditorius externus of the Raiae ;" but does not men- tion their existence in the S. Canus. Perhaps he might not have had any opportunity of dissecting this species of the Squalus. I am of opinion, that the species of shark which Lawrence and Macartney have dissected and described, was not the S. Canus, but some other species of the Squalus ; because, I have frequently had the heads of very large sharks brought to me for dissection, and have often failed in distinguishing the auditory tube, or its muscle, particularly if the animals were old. But I have always found the meatus auditorius externus, (the sinus auditorius externus of Weber) and its attendant muscle in the young dog fish. 112 In a paper on the Ear of the Squalus Canus, which was read at a meeting of the Wernerian Natural History Society of Edinburgh, on the 19th November, 1825. I have thus described the meatus : " The tube is formed of tough, elastic, membranous substance, and runs out- ward or laterad, forwards or antiniad, and downwards or basilad, a few lines more or less, according to the size of the animal, until it reaches within a short space of a membrane stretched across the tube, where it en- larges to nearly twice the size of the other parts of the tube/' " This membrane may with propriety be termed the Memhrana Vestihiili.'^ " The tube then describes an angle by running downwards, backwards, and a little outwards, until it reaches the Foramen Oblongatum^ to the edge of which it is attached in some subjects more closely than in others."* This description was chiefly taken from notes of a dissection of the external parts of the organ, in a subject in which the capillary ducts were, by some means or other, obliterated, and which led to the mistake of the tube being described as impervious ; whereas the meatus in the young animal is only rendered impervious by means of the muscle and structure of the parts forming the capillary duct, situated on the edge of the valvular membrane, under the will and controul of the animal. * The first part of this paper was published in the Edinburgh Philosophical Journal, January, 1826. 113 If a description of the Ear of the whale were to be given, as inchiding* an accurate account of the organ of hearing in all the mammalia that swim in the northern seas ; the description might possibly be correct in regard to the whale,* but would certainly be egregiously wrong, if it were to be applied to the narw al, and yet, the situation of the meatus is similar in both : but the membrana tympani of the whale is convex externally, while that of the narwal is extremely concave. And if an account of the Ear of the squalus canus in the young animal were to be given, as forming a correct descrip- tion of the whole of the shark genera, it would, in the same manner, be found to deviate considerably from the other species of that ferocious family. The very small diameter of the caliber of the meatus in the S. Canus, may perhaps be urged as an argument in favour of the non-existence of the auditory tube in this animal ; but if it be allowed that the balsena mysti- cetus has a meatus, or auditory tube, the diameter of ♦ I say possibly, because, there has as yet been no correct account given of the organ of hearing in this singularly formed animal. The Rev. Mr. Scoresby has gone so far as to deny the existence of an external orifice to the auditory tube in the whale, and none of the Journals which I have seen, have contradicted the absurd and ridiculous assertion. At the same time, while stating this fact, I by no means wish to detract from Mr. Scoresby, the merit due to him as an able and intelligent navigator ; but, when he attempts to excel as a comparative anatomist and naturalist, he certainly commits more errors than one, Q 114 which is -VW parts of an inch, and the animal forty-five feet in length ; the diameter of the caliber of the meatus forms then about the four thousand three hundred and sixtieth part of its whole length. Whereas, in the S. Ganus, where the diameter of the external orifice of the meatus in the cuticle, is only -y^^-o parts of an inch, and allowing the animal to be three feet in length, it forms then the two thousand four hun- dredth part of its length, and the other parts of the tube which measure -|^ parts of an inch, about an eight hundred and seventy eighth part of the length of the shark. So that, by this calculation, even the contracted orifice of the auditory tube in the S. Canus, is above twice the proportionate size of that in the B. Mysticetus ; and the other parts of the tube are nearly five times its proportionate size. Besides, it does not necessarily fol- low, because the S. Canus has an external meatus, or auditory tube, that the pulsations of sound must enter by that aperture. The physiological account which I have given of the membrana tympani and meatus of the B. Mysticetus in this work, will I trust, place this theory in a proper light, especially when its truth can be easily proved by dissection. TABLE III. SIZE OF THE MEMBRANA TYMPANI IN ^eb^ral ^nimal^, TAKEN FROM PREPARATIONS IN THE POSSESSION OF THE AUTHOR. TABLE III. Number or character of the Preparation. Description. Greatest Diameter. Least Diameter. 300 Preparation of the right Ear of the Balsena Mysticetus. : remark- able fine specimen Length of the membrana tympani, from its origin to its attachment to the body of the malleus, measurement in a line with the Valvular Process. Diameter of its muscular coat, taken so as to intersect the com- mencement of the process. Lines. Lines 20A Lines 19rV Do. do. minor concavity •.••••. ^ Length of the convexity of the membrana tympani, with l jg^ the cuticle entire 3 * Breadth of ditto 9 367 D. Prep, of the Ear of the B. Mysticetus, in situ, connected with the cranium) subject young, but of four feet bone. Length of the muscular coat of the membrana tympani from its origin, to its attachment as above. Breadth of ditto. The prep having been kept several years in a dry state, the con- cavities have become contracted, and therefore, their depth cannot be so well ascertained as those of No. 300. Prep, of the membrana tympani of the B. Mysticetus. Subject middle sized. Length of the muscular coat. Breadth of ditto. The concavities are considerably shrunk, but larger than those of No. 307. Lines 18rV Lines 14-'- 306 20 lines 1 8 ''ne» D. Prep, of the membrana tympani of the Narwal, or Sea Unicorn, (Monodon Monoceros.) Height of the internal convexity to the insertion 7420 inch into the malleus i 1 '"*-"• Breadth of the muscular coat of the membrane at \ _^_h__ jjjch its insertion into the malleus jiooo 10 1000 100 Prep, of the Ear of the Monkey, (Simla Sabaea ) Membrana tympani. T'oTTo" HU Prep, of the Ear of the Horse, (Equus Cabulus.) Membrana tympani. 366 10 tVoV 410 Prep, of the Ear of the Ass, (Equus Asinus.) Membrana tympani. f^^^ 1000 116 Prep, of the right Ear of the Walrus, or Sea Horse, (Trichecus Rosmarus.) Membrana tympani. iU^' 4 3 10 133 Prep, of the left Ear of the Seal, (P. Vitulina,)oBe of the finest specimens in the collection. Membrana tympani. Tlie right Ear was presented to Dr. Barclay in 1817, and is, I believe, in his museum, bequeathed to the Royal College of Sur- geons in Edinburgh. The peculiar beauty of tlie Tympano-Coch- lear Membrane exceedsthatofany prep.of theear which I haveseen. Prep, of the right Ear of the Seal, (P. Cristata,) which exhibits the best specimen of the muscles of the tympanum in this collec- tion. Membrana tympani. The left Ear was presented to Dr. Barclay in 1817, and is, I believe, in his museum, bequeathed to the Royal College of Surgeons in Edinburgh. 10 4 a n 1000 123 yoo o' _4JL8_ 10 The above measurements are taken on a scale of 1000 parts to an inch. TABLE III, CONTINUED. Number or rharacler ol'tlie Preparalion. Description. Greatest Diameter. Least Diameter. 95 Prep, of tlie Ear of the Common Hog (Sus Scrofa.) Merabrana tympiiui. 3.AA--1 I u 287 10 169 Prep, of the Ear of the Hare, (Lepus Tiraidus.) The membrana tympani is formed, as if two circles were joined ; the largest com. mences at the extremity of the rim, and continued to the whole of the manubrium of the malleus. The lesser circle is attached to the tympanal extremity of the superior line of the meatus and to the greater circle. tVVo 10 _L.Q_o, 10 183 Prep, of the Ear of the Fox, (Canis Vulpes.) Membrana tympani. There are several preparations of the Ear of this animal in the collection, which measure nearly alike. 3.9.9.-_Q 10 10 90 Prep, of the Ear of the Calf of the Bull, (Bos Taurus.) Membrana tympani. 5 9 10 3 s o.q T"o"o"o" 161 Prep, of the Ear of the Cat, (Felis Catus.) Membrana tympani 10 2 4 0-0 10 R. Prep, of the Ear of the Swan, (Anas Cygnus Mansuetus.) Mem- brana tympani. .■5 4 1 10 2 3 0-.; T03"0^ R. Prep, of the Ear of a Turkey, (Meleagris Gallipavo.) Mem- brana tympani. 3 3 .3 • .5 10 3 6 3 10 142 Prep, of the Ear of the Cock, (Phasianus Gallus.) Membrana tympani. Prep, of the Ear of a young Game Cock, (P. Gallus.) Membrana tympani. Prep, of the Ear ot an old Cock, (P. Gallus.) Membrana tym- pani. 5 2 4 4-5 100 R. 10 2 0-S 10 150 1 fi 1 10 2 10 R. Prep, of the Ear of the Partridge, (Tetrao Perdrex.) Membrana tympani. 2 6 6.3 10 tVW R. Prep, of the Ear of the Fulmer, (ProcellariaGlaciales.) Mem- brana tympani. ■> 1 4-3 10 10 R Prep, of the Ear of the Goose, (Anas Anser.) Membrana tym- pani. 3 n n ■ .5 10 2_5LP_-2 10 6 R. Prep, of the Ear of the Drake, (Anas Domestica.) Membrana tympani. 2 1 1 To "00" 10 00 R. Prep, of the Ear of a Sparrow Hawk, (Falco Nisus.) Membrana tympani. The merabrana tympani is beautifully pellucid, almost trans- parent, and in proportion to the size of the animal, more than seven times the size of that in the human subject. 3 1 i . .5 10 1 p fi-s 1009 R. Prep, of the Ear of the Common male Pheasant, (Phasianus Colohicus.) Membrana tympani. The membrana tympani in this animal is convex externally ; but not from the effect of the pulsations of sound. 3 10 9 9 2 15-1 10 A. Prep, of the Ear of the Common female Pheasant, (P, Colchicus.) Membrana tympani convex externally. 2 6 2-6 10 1 6 n 10 The above measurements are taken on a scale of 1000 parts to an inch. 118 Although the membrana tyrapani be generally con- sidered as belonging to the intermediate division of the organ of hearing ; yet, as it forms the boundary between the external and intermediate divisions, I have therefore included a description of this membrane in the present work. In this table, the convexity of the membrana tympani is not stated, the size of the tympanal rim is only given : and therefore, a considerable allowance should be made when estimating the superficial extent of this important membrane, particularly in that of the Balsena Mysticetus and the Monodon Monoceros. I am engaged at present, in forming an instrument to ascertain the degree of convexity, or concavity in the membrana tympani of various animals. An accurate knowledge of the extent of the concavity of the membrana tympani in persons, or animals of acute hearing, as well as of the size of the membrane itself, may tend to form a criterion, to ascertain the quantum and strength of the pulsations of sound ; and perhaps also, the grade of susceptibility in the portio mollis, necessary to acute auditory perception.* * The size, form, and angle of attachment of the auricle; as well as that of the meatus and its secretions, are also absolutely requisite to form au estimate of the qualities of the recipient parts of the organ of hearing in man. MEMBRANA TYMPANI BALiENA MYSTICETUS. The form of the membrana tympani in most animals, is so uniform and extremely simple, being- concave externally, and convex internally, and generally more or less of an oval figure ; that it requires very little descrip- tion in order to convey an accurate idea of the propor- tionate size and figure of the membrane in various animals, to that of the human subject. But in the Balsena Mysticetus, the membrana tympani is of so extraordinary a figure, and so much the reverse in form and position to that in other animals, or even the human subject, as to render it an object of investig-a- tion, meriting a minute and accurate description. In this animal, the membrana tympani is large and irre- gular ; convex externally, and internally of a valvular and double concave figfure. A tolerable correct idea of the internal appearance of the membrane may be formed, by supposing* a fold of a very large membrane to be taken up, and the edge of 120 this fold to run in the direction of, and forming a divi- sion of its diameter. The slender* process of the malleus, is attached by its whole length to the edge of this fold, or duplicate of the membrana tympani ; and which may be termed the Processus Valvulus (or Valvular Process). This process is kept tense by the action of the small muscles of the tympanum, while at the same time, this tension necessarily causes a correspondent slackness and depression, or concavity on each side of the process ; but which is more considerable in the one underneath the fold (when viewed from the tympanum) than in the other. The one depression I have termed the Major Con- cavity, and the other the Minor Concavity.-j- The muscular coat of these concavities forms externally two convexities, which are covered, and united by a kind of fibrous, cellular, membranous substance ; so that the two convexities form only one oblong convex surface, pro- truding considerably into the meatus, and covered by the reflection of the cuticle. J * There is also a remarkable deviation in the very figure of the malleus from that of the human subject, and which shall be fully described when treating of the intermediate division of this organ. •f- These concavities are deep in proportion to the age of the animal. J And in this manner one portion of the membrana tympani forms the minor concavity, and the other the the major concavity, and the edge of the duplicate or division between them, is termed the Valvular Process ; and these concavities ■when viewed from the meatus, or externally, are consequently of a convex figure. 121 On laying- open the meatus immediately over the membrana tympani, the parts have a very singular appearance. The cavity which is oblong, is filled with the membrana tympani, that assumes, as has been mentioned, an oblong-, convex, sharp ridged figure. When this convex substance is inspected closely, there appears underneath the cuticle* a profusion of nervous fasciculi, which shine through the thin cuticle, forming a beautiful reticulated plexus, and of which I have given a sketch in Plate V. The sharp ridged-like process is formed of a duplicate of the cuticle covering- the ex- treme convexity of the membrana tympani, and ex- tending beyond the membrane. The main branch of the nerve runs longitudinally be- tween the cuticle and the membranous substance, and the beginning of the formation of this sharp ridge, and sends ofi* numerous branches, which ramify on each side and cover the convex membrana tympani. On tearing off the cuticle, the numerous and extremely minute nervous fasciculi, are seen more distinctly than when covered ; branching in various directions and piercing the white membranous substance that is in immediate con- tact with the cuticle, and are afterwards lost in the muscular substance of the membrana tympani. * In a preparation of the meatus of this species of the whale, in my possession, the cuticle is of a brownish slate colour. R 122 When this nervous plexus, and also the membranous substance are removed, the muscular portion of the membrana tympani is seen underneath, having the ap- pearance of an oblong convex substance, divided through its shortest diameter, so that in reality it forms two convex bodies. The ends of these two convexities of the muscular portion of the membrana tympani, press so close on one another, that it is only by introducing a probe between them, that the depth of this division can be ascertained. The parts which correspond internally to this division of the muscular portion of the membrana tympani, form the valvular process or edge of the fold.* The extreme convexity of both these divisions are surmounted by a sharp ridge-like process, which runs longitudinally, and of which I have endeavoured to give a sketch in Plate VI. In this animal, the meatus auditorius externus is of great length, but very small diameter, and its use is completely reversed to that of the external meatus in the human subject. In the Bala3na Mysticetus it serves the same purpose as the eustachian tube in other animals ; to admit of the vibratory action of the membrana tympani. * In one preparation, now before me, the external division between the con- cavities formed by the muscular coat of the membrana tympani, extends uo deeper than about three-tenths of an inch, the remaining portions being closely connected until they form the edge of the Valvular Process. 123 The eustachian tube (in the whale) though short, yet performs the important office of conducting the pulsa- tions of sound into the tympanum.* Now, as the tym- panal extremity of the eustachian tube is situated obliquely in the tympanum, and also directly opposite to the valvular process of the membrana tympani ; so it may thence be inferred, that the above figure of the mem- brana tympani is admirably adapted to prevent the resilience of the pulsations of sound as they strike on the membrane ; and also cause strong vibratory action in the membrane, and correspondent action in the ossicula auditus to which the membrana tympani is firmly attached. Sir Everard Home, to whom the learned are indebted for the best account of the muscular structure of the membrana tympani in the human subject, has also given a description of this membrane in the Baleena Mysticetus, (the same species from which the above illustrations were taken) and attached a drawing of the external, and another of the internal appearance of this membrane. * It would certainly add considerably to the anatomical definition of the organ of hearing in this animal, if the situation and course of the eustachian tube were delineated, and likewise that of the large cavity adjoining to the osseous tym- panum, with its cavernous assemblage of carnese columnae and cordas tendinae, but these, with other parts of the tympanum and labyrinth, are reserved for a work which I am preparing for the press, on the Comparative Anatomy of the Organs of Vision and Hearing. R 2 124 But although few plates are more beautifully executed than the engravings of his two sketches, yet at the same time it ought to be remarked, that Sir Everard's repre- sentation of the parts are very incorrect, as well as his account of the figure and position of the membrana tympani in its relation to the ossicula auditus. In this paper of Sir Everard^s,* after stating how, and from whom he received the preparation, the subject of discussion, he gives a short description of the parts, and then flatly contradicts the account given by Hunter, of the organ of hearing in this species of the whale tribe, and endeavours to show, that there is no connexion be- tween the membrana tympani and the ossicula auditus. " Having pointed out," says Sir Everard, " that there is no direct connexion between the membrana tympani and the ossicula auditus as in other animals, and also shewn that Hunter^ unwilling to believe that there could be so great a deviation from the ordinary construction of this organ, was led into an error, which I can only attribute to his having formed to himself too strong a chain of analogies. "f * An account of some peculiarities in the structure of the organ of hearing in the Balasna Mysticetus of Linnaeus, By Everard Home, Esq. F.R.S. — Philosophical Transactions, 1812. t It might have been thought, that respect for the memory of Hunter, as well for his talents as consanguinity, would have rendered Sir Everard more wary in 125 He afterwards states, " Within the cavity of the tym- panum, close to the bony rim to which the membrana tympani is attached, there is a membranous fold fixed at one end to the centre of a slight protuberance on the concave surface of the large hollow bone, and stretched across the cavity, its loose upper edge forming a line across the centre of the hollow of the membrana tym- pani ; the other end passing beyond the cavity to be attached to the short handle of the malleus, which is situated immediately behind the membranous lining of the tympanum." According to this account of Sir Everard's, his mem- branous fold has no connexion with the membrana tympani, (indeed he expressly avows it) but merely a triangular piece of membrane affixed by its base to the inside of the cavity, and its apex or point, to the slender handle of the malleus. Now, instead of its being a seperate, unconnected membrane, it is bona fide a fold of the muscular portion of the membrana tympani itself. The edge of this fold, which I have termed the Valvular committing himself on a point where that celebrated anatomist was so deeply im- plicated; but as Sir Everard asserted his opinions on this subject, in direct opposition to that of the first Physiologist and Anatomist which this country has produced, for what he conceived to be the truth; so I hope the worthy Baronet will giant me the same indulgence claimed by himself, when I endeavour to prove, that Hunter was correct in his description, as far as he went, and that he, (Sir Everard,) in his description of this membrane, is, to say the least, inaccurate and too hasty in forming his conclusions. 126 Process, is attached to the whole length of the gracilis, or slender process of the malleus ; and one portion of it being reflected backwards and downwards, (viewing the parts from the tympanum) forms the major concavity ; and the other reflection of the muscular portion of the membrana tympani forms the lesser or minor concavity. And the parts that would necessarily hang loose, (if the fold were to be formed artificially) are attached to the body of the malleus ; which in this animal is nearly as long as any of its two processes in the adult, and longer than those of the young animal. By this means, the largest portion of the membrana tympani immediately under the valvular process, forms a very deep cul d' sac, while the parts beyond it form another of considerable less depth ; and their ends coming in contact, form ex- ternally (as a whole) an oblong convexity which protrudes into the meatus, similar to the sketch given in Plate VI. The elevation, or as it is termed, the protuberance of the osseous parieties of the tympanum, is situated in some parts about five and a half lines, and in other parts about three and a half lines from the extreme edge (or ' rim' of Sir Everard) of the osseous cavity of the tym- panum. The whole of this space is rough for the attachment of the muscular portion of the membrana tympani, and also the membranous substance formerly mentioned ; and occupied by the points of adhesion 127 which it forms, as well for strength as to allow the trans- mission of vessels and nerves to the membranous substance lying externally to, but in immediate contact with the muscular portion of the membrana tympani, and inside of the reflected cuticle lininof the meatus. This membranous substance appears to be intended to afford a bed, or protection for the nervous plexus and vessels, in order that when contraction of the fibres of the muscular portion of the membrana tympani takes place,* there may be no undue pressure on the plexus, the extremity of the minute branches of which, are lost in the muscular portion of the membrane. Sir Everard says, " From the mechanism des- cribed, it is evident that the impulses made on the membrana tympani are not immediately communicated to the ossicula auditus as in other animals, they are only communicated to the tympanum, and thence to the chord stretched across its cavity.^ '-j- To this it may be remarked, that as I have already fully explained both by sketches and description, that the membrane described by Sir Everard as attached to the malleus, but forming ac- cordii^ to his account, no connexion with the mem- * When in the act of accommodating itself to the pulsations of sound. f Of what use is the membrana tympani to this species of the whale, if Sir Everard be correct in his description and physiological illustration of the parts ? 128 brana tympani ; is not only part of that membrane, but actually forms a duplicate of the whole diameter of the central part of the muscular portion of the membrana tympani (in the Greenland whale,) so it is therefore unnecessary to recapitulate the description of the figure and position of the parts. And, from its intimate con- nexion with not only the slender process of the malleus, but likewise with nearly the whole of the body of that bone, (which in this animal is of great length and thick- ness) consequently, the pulsations of sound have the most powerful effect on the ossicula auditus, by means of their immediate connexion with the membrana tympani. And as the surface of the membrana tympani in the whale, is more than double the size of that membrane in any other animal ; so it follows, that its large double con- cave figure will increase the power of the pulsations of sound in more than a direct ratio of its diameter to that of the diameter of the membrane in other animals: because, by means of its valvular and double concave figure, the whole strength of the pulsations of sound which may enter the tympanum will be retained, until the necessary vibratory action of the membrana tympani takes place.* * Although, the pulsations of sound pass through the tympanum in order to arrive at the membrana tympani ; yet they can have little effect on the ossicula auditus, (individually) as these bones are separated from the great cavity of the tympanum, by means of a remarkable tough membrane with which it is lined. 129 When Sir Everard writes, " The membrana tympani of the whale has the means within itself of adjustment to different sounds, while the animal is under water." It may be asked, of what use can this power of adjust- ment be to the animal, if the membrana tympani have no connexion with the ossicula auditus ; especially when the pulsations of sound are conducted by the eustachian tube into the tympanum. For, according' to his descrip- tion of the parts, the membrana tympani can be of no use to hearing, at least he does not explain satisfactorily, in my opinion, how, or in what manner it is ac- complished. Sir Everard also adds : *' The long handle of the malleus is left loose." Now in the recent subject, or preparation, when carefully made, the extremity of the long handle of the malleus is always found attached to the outer edge of the osseous tympanum ; and the groove in this process, as well as the depression in the body of the malleus, occupied by the attachment of one of the small muscles of the tympanum. The long handle of the malleus is so far from being loose in its healthy state ; that the extremity of this process on the one side, and the process of the incus on the other, form the central points or fulcrum, for the motion of the ossicula auditus. 130 I have in my possession nearly twenty preparations of the Ear of the Balsena Mysticetus, of which two are entire and in situ (in liquid).* Two in the dried state, with the membrana tympani entire, one of which is in situ, and the other removed from the cranium. The remainder are sections, cut so as to show the parts to the most advantage, several of which are of the petrous portion, to show^ the large and beautiful cochlea so pre- eminently conspicuous in this animal. I have also two preparations of the membrana tympani attached to only a small portion of the osseous tympanum. In all these preparations, I have found the membrana tym- pani uniformly agreeable to the sketches and description which I have given in this article, j* As these remarks on the paper and drawings ot Sir Everard Home, on the organ of hearing in the Balsena Mysticetus, will be found correct by any person who may choose to dissect for himself, or consult my collection of preparations of the Ear of this animal: J * Prepared from the cranium of a young whale presented to me, in excellent preservation, by my late pupil Mr. B, Boulter. f I have also six preparations of the Ear in other species of the whale, J A celebrated Anatomist and Lecturer, (now no more) showed me, many years ago, the tympanum of a whale that had been presented to him as the Ear of that animal ; but of the truth of the assertion he could not be persuaded. When I showed him one or two specimens of the organ of the Balasna Mysticetus, which I had prepared, he allowed, that although his museum might be worth more than 131 so I may, perhaps, be allowed the liberty of hazarding another opinion in addition to those already made relative to the subject of discussion, namely, that the Ear of the whale from which Sir Everard took his sketches and description, was injured. And although his description and beautiful drawings might be per- fectly correct, and accurately copied from the appearance of the preparation before him ; yet, the organ of hearing in the Greenland whale, when healthy and in situ, varies considerably from his account, or representation. And also, that a full and accurate account of the organ of hearing in most animals, cannot be given from the dissection of one specimen ; there must be several, in order to form sectional views of the various parts, so as to illustrate this most intricate organ, with its unique membrana tympani. And I am convinced of the truth of this opinion, from an error into which I was once led in describing the meatus of the Squalus Canus from one preparation, in which the capillary aperture near the valvular membrane, was some way or other obliterated, and by this means, the parts had not only the appearance, but were actually such as I described. thirty thousand pounds, yet, there was no preparation of this organ in it, which could compare with my preparations, which he judged to be the most splendid in Europe. s2 132 On the suggestion of a friend, that it was possible, a deviation from this specimen might exist, I procured at various times, upwards of one hundred recent heads of the dogfish, and dissected them, and found not only that which was wanted, but also an additional muscle to secure and counteract the accidents to which the parts might be liable, from their very peculiar arrangement.* But although Sir Everard, from some circumstance or other, with which I am unacquainted, might have been led to describe the parts inaccurately; yet his previous discovery of the muscularity of the membrana tympani, is sufficient of itself to compensate fully for any errors which may be found in the above paper.-j* * For a full account of the meatus of this animal, see Table II. and description appended ; and also a magnified view of the parts in Plate IV. f The great difficulty in procuring preparations of the organ of hearing of the B. Mysticetus, renders it no easy task to give an accurate description of the parts. Hunter mentions that he equiped several young surgeons, and sent them to Greenland, in order to procure specimens of the Ear of the whale, but that they ultimately failed, I have procured situations in fishing vessels for upwards of fifty young surgeons, the whole of whom failed in procuring me any specimens of the Ear of this animal, except my late pupil, Mr. B. Boulter, to whose attention and perseverance, I am indebted for a cranium, which has furnished me with two beautiful preparations of this organ. MEMBRANA TYMPANI MONODON MONOCEROS. The arrangement of the machinery of the organ of hearing in the Narwal, affords the finest illustration of muscularity in the structure of the membrana tympani, that is perhaps to be found in the Ear of any animal ; and must ultimately (when fully known) claim the particular attention of the Anatomist and Physiologist. The membrana tympani of the Narwal is small when compared with that of the B. Mysticetus, but consider- ably larger than the membrana tympani in the human subject. It is very strong and muscular; concave ex- ternally, and convex internally, and in figure, has somewhat the appearance of the flower of the con- volvulus. As scarcely any description can convey so accurate an idea of the figure and position of the parts as a correct delineation, so I have therefore given a sketch of the appearance of the membrane and adjacent parts, taken within about an hour after the animal was killed.* * See Plate VIII. 134 The external figure of the membrane is nearly circular, the largest diameter exceeding that of the less by only about ywo-w parts of an inch. In the note attached to page nine of this work, its convexity is described as greater than its diameter ; such indeed is the appearance of the membrane in the recent state, but the measurements specified in Table III. are taken from the dried preparation, and must therefore be rather less than that of the recent subject. And even in the dried state, there is only -yo^-o parts of an inch of difference between the height or apex of the convexity, and the greatest diameter of the membrane. The apex of the convexity of the membrane, forms a strong, powerful, but small muscle, that may be termed the Terminative Muscle of the membrana tympani, and which measures only y^^-q- parts of an inch, at its in- sertion to the malleus.* There is certainly a great deviation in the figure and attachment of the membrana tympani of the Narwal from that of all other animals with which I am acquainted. It is connected to the * In the preparation of the membrana tympani of the Narwal, now before me, the Terminative Muscle, (formed by the converging and coalescing fibres of the mem- brane) measures in length about two hundred and seventy, one thousand parts of an inch, and at its formation is about one hundred and seventy, one thousand parts of an inch in breadth ; and contracts gradually to fifty-five, one thousand parts of an inch, at its insertion into the malleus. The preparation is in the dried state, and therefore soma allowance should be made for the parts forming the concavity, adhering, and thereby increasing the length of the Terminative Muscle, 135 ossicula by an extremely small but strong attachment, in such a manner, as to command and regulate, in conjunction with the muscles of the tympanum, the motions of that bone with great precision and effect. In most animals, the manubrium of the malleus is attached and firmly connected to about two-thirds of the large diameter of the membrana tympani ; but in the Narwal, the breadth of the attachment is only about the one-eighteenth of the surface of the convexity of the membrane. The malleus is of an irregular figure, and shaped some- what like that of the B. Mysticetus, but neither so long nor thick. The body of the bone which measures about three times the length of its breadth, and when in situ, and viewed from the tympanum, lies in a line with the direc- tion of the meatus, having a broad, flat, hollow, triangular process, that arises from about half the length of the malleus, and which tapers gradually to a small point that is lodged in a depression of the tympanum. The extremity of the Terminative Muscle of the membrane, is firmly attached to a tuberosity or process near the interior end or foot of the malleus, when viewed as in Plate VIII. where the half of the length of the con- verging convexity of the membrana tympani appears 136 beyond the central line of the triangular process, the extremity of which process, forms one point of the ful- crum of the ossicula, or machinery of the tympanum. The effect which this peculiarity in figure and attach- ment of the membrana tympani, the form and position of the ossicula, as well as the susceptibility of the beautiful plexus of nervous fasciculi in the tympanum, may have, in rendering the hearing of the Narwal acute, whether the pulsations of sound be conveyed by the meatus, or the enormous cavity formed by the eustachian tube ; and also its adaptation to the atmosphere, but more particu- larly to the denser medium of the ocean ; will be con- sidered at some length in a work preparing for the press, to which I have had occasion to allude in several parts of this treatise. The physiology of the organ of hearing in the Narwal, forms a more intricate and diversified subject for dis- cussion, than even that of the B. Mysticetus ; especially when we consider the extreme acuteness of hearing, and the variety of figure and position in the arrangement of the various parts of this organ ; and must therefore give a greater scope to physiological discrimination than that of any animal in the Northern Ocean.* * The above notes regard only the muscular portion (or coat) of the membrana tympani of the Sea Unicorn. TABLE IV. CONTAINING THE SIZE AND ANGLE OF ATTACHMENT OF THE AURICLE. 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"C (M I-H fH p-i CO rH (N CO •^ CO CO CO » f— 1 © rH © © ©' i"l l-H r-t 1—1 1— ( r— 1 r^ ^H 1^ '"' *"* ^H (— H i-H hI<4 -I-:?! -IrH wh m|« H|« „l^ Mf^ O ^^ O 00 »10 CO © (M © < P-t (M i-t l-H I— 1 CO CO CO r-l c^ CO Tf Tf 00 O O rH ^ © t^ 00 Q5 © •1^1 QO 00 00 05 05 Oi o © © © © © © © G" > ^ 1 z°1 " __ » 144 This Table will be found extremely useful to the young practitioner, as it furnishes a criterion to estimate the qualities of the recipient parts of the organ, from their form and size ; and by that means, he will be able to discriminate, if diminution of hearing arises from any defect or malformation in the auricle, or the meatus ; or, if it be connected with diseases of the intermediate, or the internal divisions. Before inspecting the Table, the reader should carefully peruse the remarks from page seventy-five to page eighty-six, but particularly the Six Axioms. The longitudinal, or extreme length of the auricle, is taken from the outside of the superior part of the helix to the outside of the inferior part of the lobe ; and the extreme, or horizontal breadth, from the root of the tragus to the outside of the helix in the above direction, and again, from the edge of the tragus to the outside of the helix. And by this means, the quantum of undu- latory pulsations which the auricle intercepts to convey into the meatus, can be easily ascertained. The angle of attachment which the auricle forms with the lateral parts of the cranium, was taken by an instrument made expressly for that purpose. It consisted of a quadrant with a moveable, or parallel index, the base of which applied to the parts immediately in front, and on a line with the root of the tragus. Part of the quadrant 145 was cut out, so as to admit the auricle to remain in its natural position during the period of measurement. In several cases of M. Perminutus^ which have been under my care, where, from the active habits of the individuals, secretion of cerumen took place ; the small contracted aperture of the meatus generally prevented the evaporation of its volatilized particles, and by this means, aided by the occasional acquisition of pulverized atoms floating in the atmosphere, accumulation and in- duration of the cerumen, were the usual consequences of this species of malformation in the meatus. It appears to be a principle in the application of acoustics to the human Ear, that the continuance of strong pulsations, or even the admission of the same pulsations in a large volume, as in M. Peramplus, are injurious to the sentient qualities of the portio mollis ; and hence the reason, when strong pulsations of sound are very much condensed, as in M. Perminutus, that Secretio Imper- fecta, accompanied with resilience, renders the percipient qualities of the organ callous and insensible to the stimuli of weak and soft sounds; particularly in con- versational parties. That the auricle is eminently conducive towards rendering the hearing acute, may easily be inferred, 146 thus. If an individual be five feet six inches in height, and the cahber of the meatus be fVW parts of an inch, the orifice will then form only the -^i^ part of the height of the person. And allowing the auricle to be twenty- five lines in length, it forms then the ^^-^ part of the whole height mentioned ; and from its angular attach- ment to the cranium, causes an increase of upwards of thirty times the amount of pulsations of sound to enter the meatus, than would have done, without the aid of this elegant and useful appendage. Hence the beautiful and excellent adaptation of the external, or recipient parts of this organ in man, to render the hearing- acute, by means of the symmetrical proportion of the auricle, which retains and conducts into the meatus, the quantum of pulsations of sound necessary to form acute perception ; so that pulsations which would, with- out this provision, be scarcely audible, are condensed in the auricle and meatus, and produce vibratory action in the membrana tympani, and acute auditory per- ception in the sentient parts of the organ. VELOCITY OF SOUND. Sound is produced by the vibration, or action of a substance on the surrounding' atmosphere ; and is more audible in dry, than in wet weather. This may perhaps be ascribed to the electric fluid being in greater quantity, and, therefore, more easily excited in a dry than in a moist atmosphere. Sound does not travel with equal velocity from the point of emanation, to the point at which it becomes inaudible. Thus in the line A. C. B.,* let A. be the situation of the vibratory body, and B. the point at which the pulsations of sound become nearly inaudible to the acute Ear, and C. be a point at three-fourths of the length of the line when measuring from A. to B. It is evident that the pulsations of sound must travel at a much less velocity per second, from the point C. to the point B. than from the emanating point A. to the point C. by reason of the surrounding atmosphere. -j* * A C B, f In an excellent paper read before the Royal Society, London, Dr. Young calculates that "Sound must decay in the duplicate ratio of the distance." Philosophical Transactions, 1800. 148 As the velocity of sound has engaged the attention of the learned in various countries, and as it is desirable to compare their different statements, so I have, there- fore, for reasons formerly mentioned, extracted the following Tables from the Edinburgh Philosophical Journal, which are inserted as accompanying notes to this article. These tables contain, no doubt, the result of many excellent experiments ; but still, a great deficiency exists in the various accounts hitherto given, viz. a correct description of the figure, and geognosy of the country where the experiments were made. And this descriptive analysis of the site, of the experiments, and also the parts adjacent should premise, or follow every essay on the subject. According to the geological structure, as well as the figure of the country, and also the state of the atmosphere, and the intensity of the pulsations, the velocity of sound will be retarded or accelerated. And according to the distance, when within the range of auditory perception, which the auditor is placed from the vibratory body, so is the degree of softness and harmony of the sound heard. Thus, if a field-piece be fired close to a person, the pulsations of sound produced by the explosion, will cause strong vibratory action in the membrana tyrapani 149 of the auditor so placed, and which will be for some time painfully disagreeable. But if the same person A TABLE SHEWING THE RESULTS OF EXPERIMENTS ON THE VELOCITY OF SOUND, AS OBSERVED BY DIFFERENT PHILOSOPHEHS.* Velocity of Sound per Names of Observers. niude. made. Feet. Second in I'eet. 1660 France, Italy, 5905.8 1469.88 1184.44 Florentine Philosophers,'' Walker,"^ 1698 England, France, 2624.8 6906.50 1305.83 1151.63 Cassini, Huygens, &c,'' Flamstead and Halle,e England, 16405.0 1141.78 Derham,f < 1704 i 1705 1 England, < 5249.6 to 6562. ? 1141.78 French Academicians, e 1738 France, < 75177.55 & 93593.8 ? 1092.57 at 32oF. Blanconi, ^ 1740 Italy, 7874.0 1043.35 La Condamine, ' 1740 Quito, 67401.58 1112.25 La Condamine,"^ 1744 Cayenne, 129366,54 1174.59 T. F. Mayer,! 1778 Germany, 3702.40 1105.69 G. E. Muller,'" 1791 Germany, 8530.6 1108.97 Epinoza and Banza," . . 1794 Chili, 53627.94 1168.50 t Benzenberg-, ° 1809 Germany, 29765.23 1092.57 at 32° Arago, Mathien Prony,? 1822 France, 61065.97 1086.0 Moll, Van Beek, and > 1 Kuytenbrower,** . . S 5 1089.7445 at 32° t F. dry air. 1823 Netherlands, 5797290.76 * Mersenne de Arte Ballistica, prop. 39. ^ Tentamina Experim. Acad. del. Cimento, L, B, 1738, part 11. p. 116. '' Phil. Trans. 1698, No, 247. ^ Duhamel, Hist. Acad. Reg. 1. ii. sect. 3. cap. ii. ^ piiji^ Trans. 1708 and 1709. f Id. ibid, s Mem. de I'Academie des Sciences, 1738 and 1739. ^ Comment. Bononienses, vol. ii. p. 365. ' La Condamine, Introduction Historique, &c. 1751, p. 98. ^ Mem, de I'Acad, Royale des Sciences, 1745, p, 488. ' J, T. Mayer, Praktische Geometric, Gottingen, 1792, b. i. p. 166. ™ Muller, Getting. Gelehrt. Anzeige, 1791, St. 159, et Voigts Magazin, &c, b. 8. st, i, p, 170, " Annales de Chimie et de Phys. t. vii. p. 93. ° Gilbert's Annalen, neue Folge, b, v. p. 383. p Connoissance des Tems, 1825, p, 361. * From Von Moll's Memoir on the Velocity of Sound in Phil. Trans, for 1824, part ii. t This account in the Edinburgh Philosophical Journal varies from that of the Journal of Science. " From Experiments performed lately at San Jago, In Chili, by M. D. Josef de Epinosa, and D. Felipe Bauza, it appears that sound moves with a velocity of twelve hundred and twenty.seven English feet in a second ; the air being at a temperature of 73.° 5. Fahr. Barometer 27. 44 inches. — See Journal of Science, Vol. VII. page 369. 150 were to be at a considerable distance from the gun when fired, the pulsations of sound would then become softened and in harmony with, and agreeable to the perception of hearing in the auditor. And hence the stunning effect of a highland pibroch, or march, or even a national tune, when played on the full-sized highland pipes in a small apartment ; whereas when the same instrument is used on the wide and blooming heath, the notes though sharp and strong, acquire, when at a little distance from the auditor, a melody and sweetness, particularly agreeable to the Scottish Ear. The atmosphere is not the only medium through which the pulsations of sound are conveyed. The experiments of Monroe and Robison confirm the great capability of water in the transmission of sound. Dense substances have not only the quality of transmitting the pulsations of sound, but also that of increasing their velocity. Thus, an ear-trumpet will not only retain, condense, and convey into the meatus a greater quantum " A very valuable and elaborate series of experiments on the velocity of sound has been made at Madras, by Mr. Goldingham. Various different measures of the velocity of sound had been obtained by different observers, but the discrepancies in their observations were not supposed to arise from the condition of the atmosphere. Mr. Goldingham made his experiments with two guns, at the distances of 29,547 feet and 13,932.3 feet. They were twenty-four pounders charged with eight pounds of powder, and the experiments were continued during the latter part of 1820, and the whole of 1821. The following table contains the 151 of the pulsations of sound than the auricle, in proportion to the size of the external orifice of the instrument: but, also, increase the velocity, according to the quality of the substance of which the trumpet is made ; if it be made of silver, the velocity will be increased upwards of eight times that of the common atmosphere ; substance of these numerous and well-conducted experiments ; and it is curious to remark, how the velocity gradually increases towards the middle of the year, and again gradually diminishes. Mr. Goldingham conceives that this regularity would be still greater, with the mean of several years observation." Months. Barometer in Inches. Thermometer, Fahr. Hygrometer, dry. Velocity of Sound in a Second in Feet. January, 30.124 79° .05 6° .2 1101 February, 30.126 78 .84 14 ,70 1117 1 March, 30.072 82 .30 15 .22 1139 1 April, 30.031 85 .79 17 .23 1145 May, 29.892 88 .11 19 .92 1151 June, 29.907 87 .10 24 .77 1157 July, 29.914 86 .65 27 .85 1164 August, 29.931 85 .02 21 .54 1163 September, 29.963 84 .49 18 .97 1152 October, 30.058 84 .33 13 .23 1128 1 November, 30.125 81 .35 8 .18 1101 1 December, 30.087 79 .37 I .43 1099 1 "Mr. Goldingham concludes, that for each degree of the thermometer 1.2 feet may be allowed in the velocity of sound for a second ; for each degree of the hygrometer 1.4 feet; and for one-tenth of an inch of the barometer 9.2 feet. He concludes that ten feet per second is the difference of the velocity of sound between a calm and in a moderate breeze, and 21 j feet in a second, or 1275 in a minute, is the difference, when the wind is in the direction of the motion of sound, or opposed to it." See Phih Trans. 1823, and Edinburgh Philosophical Journal, 1824, 152 but if it be made of iron or glass, the velocity will be increased to nearly sixteen times that of the atmosphere ; and hence, one cause at least, of the great diminution of hearing- which takes place when the ear-trumpet has been used any length of time. The blighted ceruminous glands, as well as the callous state of the percipient parts of the organ, may be attributed to the great quantum of pulsations of sound compelled to enter the meatus by means of the trum- pet ; and if it be taken into account, that these pulsations are not only condensed, so as to contain upwards of ten, nay, even sometimes twenty times the quantity, which the auricle conveys ; and that when to the condensation of these pulsations, the velocity is likewise (by means of the substance of the trumpet) increased, nearly sixteen times that of the atmosphere ; we should, therefore, be no longer surprised at the fatal influence of this instrument, which on its first application, cherishes delusive hopes in the patient, followed ul- timately by the most baneful and paralysing effects on the various parts of the organ. For these reasons, I would recommend the greatest caution to the prac- titioner, in the application of ear-trumpets ; which ought never to be used until all other modes of treat- ment have failed. FORMULiE. No. I. R. Unguent. Quass. §i. * Nitras Potassse 3ij • Aloes. Terebinth. Van. a a 3ij« M. et adde. Iodine 3ij. M. ft. Unguentum. Great care must be taken in the preparation of this medicine, which is to be strained while hot, and poured into a seperate vessel before the Iodine is added ; the whole to be stirred with a glass, or wooden spatula, until the mineral be dissolved. The ointment is then to be carefully poured into a stopper bottle ; in which it is to be kept, until used. For further directions see page 49 of this work. No. II. R. 01. Copaiba, ^i. Iodine 5i« m. ft. Linimentum. The stimulating qualities of the essential oil is assisted by the addition of the Iodine ; but it must be used with * See Formula IV, 154 great caution ; and if there be the least appearance of discharge from the meatus, the use of this liniment is then totally inadmissible. No. III. R. Tr. Ammon. Valer. gtt. xxx. Aquae Fontana ^iss. m. ft. haust. This draught is sometimes a very valuable auxiliary to the other medicines mentioned ; the quantity of the Tr. to be varied according to the age and constitution of the patient. No. IV. R. Quassiae Ligni. ^ij . Adipis Suilli §viij. M. ft.Ung. Let these ingredients be put into a glazed pot, and the whole in a sand bath during six or seven hours ; and then strain it while hot. To be applied, as directed, to the meatus when gently warmed, in order to stimulate the ceruminous glands. I have also used this prepara- tion with great benefit in cases of diseased meibomian glands, applied every evening in a liquid state. No. V. R. Antimon. Tartar, gr. ij. Aquae Fontana §vi. M. ft. M. If the patient be confined to his room, let him take a table spoonful every four hours ; but if circumstances 155 do not allow confinement, let a small wine-glass full be taken every night at bed time. This mixture will be found sometimes very efficacious in exciting* the ceru- minous glands to healthy action. No. VI. R. Nux Vomic. |i. Aquae Ammon. ^iv. M. ft. Tr. Let this tincture be strained, after fourteen days maceration. To be applied behind, and around the auricles, so as to stimulate the branches of the portio dura, &;c. and thereby assist in exciting the ceruminous glands. No. VII. R. Mel opt. buUient. §iij. Iodine 3i. M. ft. Vug. To be applied to the meatus as directed. In a very obstinate case of diminution of hearinp-, (Secretio Imperfecta) I succeeded in restoring the secretion of cerumen by means of the Pil. Hydrarg. and the following draught. R. Tr. Ipecac, gtt. xv. — Opii. gtt. XX. m. ft. haustus. summendus omni nocte. The application of all or any of these ointments, require great care and attention in the practitioner, in order that 156 the parts may not be stimulated beyond what is consistent with healthy action. It will, therefore, be necessary to pay particular attention to the grade of sensibility in the meatus. And also, that the application of any of these ointments be assisted, either by the pill mentioned in page thirty-one of this work ; or the mixture of tartarized antimony, or such other medicine as the nature of the case may require, agreeable with the directions laid down in this volume, and in the Guide, and Illustrations of Acoustic Surgery. EXPLANATION OF THE PLATES. PLATE I. Section of the meatus of the left Ear of an adult ; with the membrana tympani entire, and the ossicula attached. The parts are divested of the cuticle, but the integuments and ceruminous glands remain, shrunk and dried. PLATE II. Section of the osseous part of the meatus of the left Ear of an adult ; and also of the tympanum, eustachian tube, vestibule, and semicircular canals. This sketch, and that of Plate I. is chiefly designed to shew the position of the Depressional Curve, formed by the angle of the osseous part of the auditory tube. PLATE III. Section of the osseous parts of the meatus of the right Ear of the Phoca Vitulina, with the membrana tympani entire and ossicula attached ; in order to illustrate the uses I have assigned to the Depressional Curve. PLATE IV. Fig. I. — Head of the Squalus Canus, natural size. A. The orifice of the right meatus auditorius externus. B. The left orifice. Fig. II. — Longitudinal section of the tube of the left meatus ; parts magnified. a. The external orifice. . b. The end of a bristle passed into the superior part of the tube. 158 c. Tube slit open so as to shew the capillary aperture and the position of the reflected portion of the tube forming the valvular membrane, which I have termed the Mtinbrana Vestibuli. d. The parts of the tube inferior to the valvular mem- brane laid open, showing the second capillary aperture, or sphincter in the tube. e. The Membrana Labyrinthi. f. The membranous tube of the meatus descending into the vestibule. g. g. Position of the superior parts of the cartilaginous cranium. h. The origin of the muscle. PLATE V. Sketch of the external appearance of the oblong convex Membrana Tympani of the Baleena Mysticetus, showing the reticulated nervous Plexus lying imme- diately below the cuticle. PLATE VL Appearance of the parts in Plate V. when divested of the cuticle, nervous plexus, and inter-membranous substance, by which means, the muscular coat is completely shown, with the fissure dividing the convex membrane into two convex bodies ; forming internally, the Valvular Process, and the Major and Minor Concavities. PLATE VIL Sketch of the internal appearance of the Membrana Tympani, of the Balsena Mysticetus ; taken from the Tympanum. a. a. a. Origin of the muscular coat of the membrana tympani. 159 b. b. The Valvular Process, edge of the fold or duplicate of the muscular coat. c. The Major Concavity , d. The Minor Concavity. e. The long handle of the malleus divested of the muscle and membrane which lines the tympanum, in order to show the parts. f. The short, slender or gracilis process of the malleus imbedded in the substance of the valvular process. g. The Incus. h. The body of the malleus, i. Stapedius muscle attached to the stapes. k. Section of the parieties of the tympanum, more than half of which is cut off. 1. Petrous portion of the bone. m. Meatus auditorius internus. n. The situation of the cochlea. o. Attachment of part of the membrana tympani to the body of the malleus. p. Situation of the Fenestra Rotunda. PLATE VIII. Sketch of the unique membrana tympani of the Monodon Monoceros, with the beautiful reticulated nervous fasciculi, covering the great valve of the tym- panum, and which I have termed the Plexus Jeffrayanis. The branches of the plexus are seen concentrating and attached to the Tympano Cochlear Membrane. PLATE IX. Sketch of the appearance of the Plexus Jeffrayanis, seen from the eustachian tube. This beautiftil nervous plexus is covered by a reflection of the delicate membrane 160 that lines the tympanum, and is seen with its numerous reticulated branches as distinctly through the membrane, as it is represented in the sketch, which was taken about an hour after the animal was killed. The dissection consisted merely, in laying open the cavity of the tym- panum longitudinally ; on which a full view was obtained of this unique appendage to the sentient parts of the organ. PLATE X. Longitudinal Section of the Membrana Tympani of the Balsena Mysticetus ; natural size.* A. Major Concavity. B. Minor Concavity. CO. Section of part of the meatus. D. D. Part of the cavity of the osseous tympanum. E. E. Portions of the osseous parieties of the tympanum. a. a. Valvular Process. b. b. b. Section of the muscular coat of the membrana tympani, showing its course, and also, the formation of the Valvular Process. CO. The situation of the inter-membranous substance, parts swollen from being kept in fluid. d. d. d. d. Course of the cuticle in the meatus, and also its reflection over the membrana tympani. * This Plate was added after the description of the Membrana Tympani was printed, in order to illustrate more fully the figure of this complex membrane. THE END. PRINTED BY CONSITT AND GOODWILL, B0WL4LLEY"LANE, HULL. T'late. I. En^i^ hy Consitt & Good-will DrB-wn-iy 1 .B-uckana^. G-"M. J^T^J^l^l^Z/^/Ul/ ^^C^^L P/^d^. (siW^€^lA. 76J. r/^ 7\^aiu7-ccl S^.ze, FlateII. Dyavjx- l>-v- T 7t"i. ■''r:\-rT; ji C^M." Enrf^iy Ccnsitt &i &oedvrLlL Hull. FCATK.JJZ. Dri-wm tj7 T.Biicliaaiii.C.M. Euo'fijv Cciisitt &r Soocb-JiXLHiin.. o. a^l/^/ r^y^^^^i^^t^ ^^^x^^^^^^^^^^^/^y^/^^/^^ Y^a> Plxte. jr. Fi^.i. Fi^.l. a, ^ Dia-vm tj? XrB'iiiUisii .CM . ailyC' Pl.i tje . V DriwE.'faj-T B-icttjioji C-M, J^ng^ty ConsiU. & Go&iwilL iirrul. Pl.ATE VI. Dn'wn iy T. B 11 ctana-T. . C ". M . Eng^lrv Cousin Sf G-ooi-vnlU Plai-e. vn . ^^i^m^/ }/^^A '^f/"^/')/7//r^p/7 ^j//p/^/i^^^.^_ ILL13iJLVX,r #' Plate. IX. DriL-.«ii tjr T. BuchanBn. C.IT. En^a-veo. iy : LfcG3oivri.ll. /7 a^miy^, j^t^ty/z^Wy, ■^ ^A rL^rs. K . Drawnlnr T- Biarluinaai .CM. Erv2 ^tv Coiisi1i& jcod-*riil.HuIl. ^^^^ ^^^ ^ 7Lmi/?a^-/i ^y^zmM^^ 'T ERRATTA. Page xi, line 18, for ' difference' read ' deference.' — xii, — 27, for ' herpatic' read ' herpetic' — 9, — 14, for • manuubriuni' read ' manubrium.' — 9, note, for ' Plate VII.' read ' Plate VIII.' — 17, line 1, dele and. — 29, — 11, for ' feelings' read ' feeling.' — 36, note, for ' perulent' read ' purulent.' — 69, note, for ' Rev. Mr.' read ' Rev. J. Colquhoun.' — 75, note, for ' pressura,' read ' pressurse.' — 80, note, for ' pressura,' read ' pressuras.' — 100, note, for 'Rev. Mr.' read ' Rev. W. Scoresby.' — 102, line 14, for ' oliaginous' read ' oleaginous.' — 113, note, for 'Rev. Mr.' read ' Rev. W. Scoresbv.' EXPLANATION OF THE PLATES. G. in Plate X. Course of the undulations of sound from the eustachian tube to the membrana tympani. COLUMBIA UNIVERSITY LIBRARIES This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the library rules or by special arrangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE 1 ■ 1 C2a(946)MIOO o o =^ ,-.==0 o=— > Ol^^i: 00 ^ IV> 3J N> " rV LIBRARIES 193 KF/2-3 Siir