judice to the functions of the organ.

Mr. P-, a medical ftudent at St. Thomas's Hospital, of the age of twenty years, applied to me, in the winter of 1797, while he was attending a course of anatomical lectures, requefting my opinion upon the nature of a complaint in his ear, which had long rendered him flightly deaf.

Upon inquiring into the nature of the fymptoms which had preceded, and of thofe which now accompanied the disease, he informed me, that he had been fubject from his infancy to pains in the head, and was attacked, at the age of ten years, with an inflammation and fuppuration in the left ear, which continued difcharging matter for feveral weeks: in the pace of about twelve months after the first attack, fymptoms of a fimilar kind took place in the right ear, from which alfo matter iffued for a confiderable time. The difcharge in each inftance was thin, and extremely offenfive to the Amell; and, in the matter, bones or pieces of bones were obfervable. The immediate confequence of thefe attacks was a total deafnefs, which continued for three months; the hearing then began to return, and, in about ten months from the laft attack, was restored to the state in which it at prefent remains.

Having thus defcribed the difeafe and its tymptoms, he gave me the following fatisfactory proof of each membrana tympani being imperfect. Having filled his mouth with air, he clofed the noftrils, and contracted his cheeks: the air, thus compreted, was heard to rush through the meatus auditorius, with a whiftling noife, and the hair hanging from the temples became agitated

by the current of air which issued from the ear. To determine this with greater precifion, I called for a lighted candle, which was applied in turn to each ear, and the flame was agitated in a fimilar manner.Struck with the novelty of these phænomena, I wifhed to have many witnefles of them, and therefore requefted him, at the conclufion of the lecture upon the organ of hearing, to exhibit them to his fellow ftudents, with which request he was fo obliging as to comply.

It was evident from thele experiments, that the membrana tympani of each ear was incomplete, and that the air iffued from the mouth, by the eustachin tube, through an opening in that membrane, and efcaped by the external meatus.

To determine the degree in which the membrana tympeni had been injured, I paffed a probe into each ear, and found that the membrane on the left fide was entirely deftroyed; fince the probe struck against the petrous portion of the temporal bone, at the interior part of the tympanum, not by pafling through a small opening; for, after an attentive examination, the space ufually occupied by the membrana tympani was found to be an aperture, without one trace of membrane remaining.

On the right fide alfo, a probe could be paired into the cavity of the tympanum; but here, by conducting it along the fides of the meatus, lome remains of the circumference of the membrane could be difcovered, with a circular opening in its centre, about the fourth of an inch in diameter.

From fuch a deftruction of this membrane, partial indeed in one ear, but complete in the other, it

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might

might be expected that a total annihilation of the powers of the organ would have followed: but the deafnefs was inconfiderable. This gentleman, if his attention were exerted, was capable, when in company, of hearing whatever was faid in the ufual tone of converfation; and it is worthy of remark, that he could hear with the left ear better than with the right, though in the left no traces of the membrana tym pani could be perceived.

When attending the anatomical lectures alfo, he could hear, even at the most diftant part of the theatre, every word that was delivered; though, to avoid the regular and conftant exertion which it required, he preferred placing himself near the lecturer.

I found, however, that when a note was ftruck upon the pianoforte, he could hear it only at twothirds of the diftance at which I could hear it myfelf; and he informed me, that in a voyage he had made to the Eaft Indies, while others, when fhips were hailed at fea, could catch words with accuracy, his organ of hearing received only an indiftinct impreffion. But the most extraordinary circumftance in Mr. P's cafe is, that his ear was nicely fufceptible of mufical tones; for he played well on the flute, and had frequently borne a part in a concert. I fpeak this, not from his own authority only, but alío from that of his father, who is an excellent judge of mufic, and plays well on the violin: he told me, that his fon, befides playing on the flute, fung with much tafle, and perfectly in tune.

The flight degree of deafness of which Mr. P complained, was always greatly increafed by his

catching cold: an effect which feems to have arifen from the meaties being clofed by an accumulation of the natural fecretion of the ear; for it frequently happened to him, after he had been fome time deaf from cold, that a large piece of hardened wax, during a fit of coughing, was forced from the ear, by the air ruthing from the mouth through the euftachian tube, and his hearing was inftantly restored.

From bathing likewife he fuffered confiderable inconvenience, unless his ears were guarded against the water, by cotton being previously forced into the meatus. When this precaution was neglected, the water, as he plunged in, by rufhing into the interior parts of the ears, occafioned violent pain, and brought on a deafnels, which continued until the caule was removed, that is, until the water was difcharged: but he had acquired the habit of removing it, by forcing air from the mouth through the ear.

In a healthy ear, when the meatus auditorius is stopped by the finger, or is otherwife closed, a noife fimilar to that of a diftant roaring of the fea is produced: this arifes from the air in the meatus being compreffed upon the membrana tympani. In the cafe here defcribed, no fuch fenfation was produced: for, in Mr. P's ear, the air, meeting with no impediment, could fuffer no compreffion; fince it found a paffage, through the open membrane, to the mouth, by means of the enftachian tube.

Mr. P was liable to the fenfation commonly called, the "tecth being on edge," in the fame degree as it exifts in others; and it was produced by fimilar acute founds, as by the filing of a faw, the rub

bing of filk, &c. Its occurring in him feems to difprove the idea which has been entertained of its caufe; for it has been thought, that the clofe connection of the nerve called the corda tympani with the membrana tympani, expoled it to be affected by the motions of the malleus; and that, as it pafled to nerves connected with the teeth, they fuffered from the vibratory state of the nerve, produced by the agitations of the membrane. But, in this cafe, as the membrane was entirely detroyed on that fide on which the fenfation was produced, fome other explanation must be reforted to; and I fee no reason why this effect fhould not be referred to that part of the auditory nerve which lines the labyrinth of the car, which, being impreffed by acute and difagreeable founds, would convey the impreffion to the portio dura of the lame nerve, and to the teeth with which that nerve is connected.

The external ear, though two diftinct mufcles are inferted into it, is capable, in its natural ftate, of little motion; however, when an organ becomes imperfect, every agent which can be employed to increase its powers is called into action; and, in the cafe here defcribed, the external ear had acquired a diftinct motion upward and backward, which was obfervable whenever Mr. P— listened to any thing which he did not diftinely hear. This power over the mufcles was fo great, that when defired to raife the ear, or to draw it backwards, he was capable of moving it in either direction.

This cafe is not the only one of this defcription which has come under my oblervation; for another gentleman, Mr. A-, applied to

me under a fimilar complaint (but in one ear only), proceeding from fuppuration, and producing the fame effects. This gentleman has the fame power of forcing air through the imperfect ear; fuffers equally from bathing, if the meatus auditorius be unprotected; and feels, even from expofure to a ftream of cold air, very confiderable pain. The only difference I could obferve was, that in Mr. A's cafe, the defect of hearing in the difeafed organ was fomewhat greater than in the former; for though, when his found ear was clofed, he could hear what was faid in a common tone of voice, yet he could not diftinguish the notes of a piano forte at the fame diftance: a difference which might have in part arifen from the confufed noife which is always produced by clofing the found ear; or becaufe, as he heard well on one fide, the imperfect ear had remained unemployed, and confequently had been enfeebled by difufe.

From thefe obfervations it seems evidently to follow, that the lofs of the membrana tympani in both ears, far from producing total deafnels, occafions only a flight diminution of the powers of hearing.

Anatomifis, who have deftroyed this membrane in dogs, have afferted, that at firft the effect on the fenfe of hearing was trivial; but that, after the lapfe of a few months, a total deafnefs enfued.-Baron Haller alfo has faid, that if the membrane of the tympanum be broken, the perfon becomes at firl hard of hearing, and afterwards perfectly deaf. But, in thefe inftances, the deftruction must have extended farther than the membrana timpani; and the labyrinth muli

have fuffered from the removal of the flapes, and from the confequent difcharge of water contained in the cavities of the internal ear; for it has been very conftantly observed, that when all the fmall bones of the ear have been difcharged, a total deafness has enfued.

It is probable, that in inftances in which the membrana tympani is deftroyed, the functions of this membrane have been carried on by the membranes of the feneftra ovalis and feneftra rotunda: for, as they are placed over the water of the labyrinth, they will, when agita'ed by the impreflions of found, convey their vibrations to that fluid in a fimilar manner, though in fomewhat an inferior degree, to thofe which are conveyed by means of the membrana tympani and the small Lones which are attached to it; and thus, in the organ of hearing, each part is admirably adapted, not only to the purpofe for which it is defigned, but alfo as a provifion against accident or difcafe; fo that, whenever any particular part is deftroyed, another is fubftituted for it, and the organ, from this deprivation, fuffers but little injury in its functions.

It seems that the principal ufe of, the membrana tympani is, to modify the impreffions of found, and to proportion them to the powers and expectation of the organ. Mr. P had loft this power for a confiderable period after the deftruction of the membrane; but, in procels of time, as the external ear acquired the additional motions I have defcribed, founds were rendered, stronger or weaker by them. When, therefore, he was addreffed in a whitper, the car was feen immediately to move; but, when the tone

of voice was louder, it then remained altogether motionless.

Obfervations on the Signs exhibited by Animals, indicative of Changes in the Weather, by Signor Toledo, an Italian Author; from the Au nals of Agriculture.

than ufual abroad from their holes, fly about in great numbers, and to a greater distance than common, it announces that the following day will be warm and ferene; but if they enter the houfes, and fend forth loud and repeated cries, it indicates bad weather. If the owl is heard to fcream during bad weather, it announces that it will become fine. The croaking of crows in the morning indicates fine weather. When the raven croaks three or four times, extending his wings, and thaking the leaves, it is a fign of ferene weather. It is an indication of rain and ftormy weather when the ducks and geefe fly backwards and forwards, when they plunge frequently in the water, or begin to fend forth cries and to fly about. If the bees do not remove to a great diftance from their hives it announces rain; if they return to their hives before the ufual time, it may be concluded that it will foon fall. If pigeons return flowly to the pigeon-houfe, it indicates that the fucceeding days will be rainy. It is a fign of rain or wind when the Sparrows chirp a great deal, and make a noife to each other to aflemble. When fowls and chickens roll in the fand more than ufual, it announces rain; the fame is the cafe when cocks crow in the evening, or at uncommon hours. Peacocks which cry during