Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/654

 T I N

T I P

Ing filled with a certain fpecies of found, cannot admit other founds, unlefs they are very violent.

The antients imagined that this fymptom was produced by the motion and agitation of the air which was included in the ear, and fuppofed this agitation to be occafioned by flatulen- cies and vapours being conveyed into the ear, and that thofe flatulencies arofe either from the whole body, as in fevers ; or from any particular part, as the ftomach, or brain ; or from pituitous humours lodged in the cavities of the ear ; and from the differences of thefe they attempted to account for all the various noifes heard in this diforder, as if they were in fome fort real : but when we confider the nature of the noifes heard in this dif temperature of the ear, fuch as the loud roaring, or the murmuring of waters, and the jangling of bells, wefhall eafily conceive thefc can be no real founds ; and it is in- deed very evident that they do not arife from either wind, or any other matter, finking the membranes externally. As a Tinnitus confifts in the hearing a found which either is not real or exifts only within the ear, in order to conceive the meaning of this, we are to confider that the action of hearing confifts in the agitation of the immediate organ ap- pointed for that purpofe ; and it is fufficient to produce a found that that organ is agitated, whether it be by the air or not. In order to determine what may be the caufe of this agitation, we need only examine what are the diforders in which ^Tinnitus ufually occurs ; we fliall find thefe to be inflammations, and abfceiles of the tympanum and labyrinth, and the diforders of the meatus auditorius. Inflammations of the tympanum and labyrinth neceffarily produce agitations in the fpiral la- mina and in the femicircular ducts, either by tenfion of the membrances, or by the vapours which tranfpire, and mix themfelves with the air in the tympanum. Acrid fubftances, worms, extraneous bodies, a conftnetion of the meatus fucceeding a diftenfion of the glands, and in general every thing that can caufe in the meatus auditorius, pain, and the other fymptoms before defcribed, agitate the membrane of the meatus, and the membrana tympani ; and this agitation is able to communicate itfelf to the immediate organ of hearing.

The fecond fpecies of Tinnitus is when we perceive a real found which is formed within the ear itfelf: thus we hear a humming noife when we flop our ears. This noife is caufed by the friction of the hand, or by the compreflion which in- fluences the fkin and cartilages, whofe parts being put into motion may produce an agitation there. The elaiticity of the air alfo and the tranfpired matter from the hand, mixing with the internal air in the meatus, may alfo ftrike the organ, tho' not ftrongly, yet fumciently to occafion a noife, as the offend- ing matter is fo near.

Commotions of the cranium, and diforders which contract the meatus, may alfo caufe a Tinnitus in the ear. Several perfons alfo are fubject to a peculiar noife in the ear, which is plainly a pulfation ; this ufually affects them moft after exercife, and may very often be heard by other perfons, who place their heads near the difeafed perfon's ear : this is unqueftionably the true pulfation of a dilated artery, fince it always regularly keeps time with the heart.

tho' the humming noife is very ltrong, yet the organ of hear- ing is itfelf no way diftempered ; fuch are thofe of perfons in deliriums in fevers, and of fuch as are fubject to epileptic fits ; thefe laft ufually hear a humming in their ears, before they are attacked with a fit, and this feems wholly produced by the agitated fpirits, which difturb thofe parts of the brain where the extremities of the auditory nerve terminate. The Tinnitus are therefore of two kinds ; the one proceeding from adiftemperature of the organ of hearing, the other from a diforder of the brain ; and the cure is to be attempted accord - ingly. In. the fharper Tinnitujfes> which are ufually occa- fioned by inflammations and pains in the ear, where the parts are ufually very tenfe and dry, we mull ufe the fame means as in acute pains, and tenfions of the membrana tym- pani ; but in dull humming heavy noifes, which are ufually occafioned by rheums and fuppurations, where the membranes are relaxed, we are to ufe the fame remedies which give relief in pains occafioned by cold : After which it will be no diffi- culty to chufe the moft proper, while we have a due regard to the circumftances, from which the more juft indications may be taken. Du Verney.
 * There feem alfo to be fome fpecies of Tinnitus, in which,

TINNUNCULUS, in zoology, the name of one of the Ionc- winged hawks, called by others Cencbris, and inEngiifh, Ke- ffrei, Stamel, or JPtndbover.

It is about the fize of a common pigeon. Its bill is fhort, crooked, and very fharp, and covered with a yellow fkin at the top ; near this the bill is white, elfewhere it is blue. Its tongue is bifid ; its mouth very wide, and its palate blue. Its head is large and flatted, and is of an afh-colour, with longitudi- nal ftreaks of black. Its back and wings are brown, variegated with black fpots; its rump is grey, with fome tranfverfe black fpots ; and its breaft and belly of a pale ruft-colour,

• with a few longitudinal ftreaks of black. Its tail is long and pointed, its tip of a pale ferrugineous hue, with a broad tranfverfe ftreak of black over it ; and the reft of the tail is a mixed grey and brown, with black fpots and ftreaks. Its legs

and feet are of a fine yellow, it builds in hollow oaks and lays four egs, which are white, variegaced with a number of final 1 red fpots. It feeds on partridges and other birds. Ray Ornitho!. p. 50.

T1NTINNABULUM, among the antients. See the article Bell.

TIN US, Laurujline, in botany, the name of a genus of trees the characters of which are thefe : The flower confifts of only one leaf, and is of the rotated kind, and divided into many fegments at the edges. The center of the flower is perforated by the pointal of the cup, which finally becomes an umbili- cated fruit, of the fhape of an olive, containing a pear- fafliioned feed.

The fpecies of Tinus, enumerated by Mr. Tournefort, are thefe: 1. The common Laurujline. 2. The Laurujiine with nervous leaves. And 3. The fmall-leaved Laurirflinc. Town. Inft. p. 607.

TIPHLE, in zoology, a name by which fome authors exprefs the acus, or tobacco-pipe fifh. Belton. de Aquat. 446.

TIPIOCA, a name given by fome authors to a fort of cream or flower made from the yucca or manihot-root, by maceration of it in water, after expreffing the juice.

TIPSARIA, or Tapsaria, a word ufed by fome medical writers for barley-water.

TIPUL, in natural hiftory, a name given by the people of the Philippine iflands, to a fpecies of crane common there, and fo tall, that when it ftands erect, it can look over a man's head.

TIPULA, in natural hiftory, the name of a genus of fly, re- markable for the great length of its legs, and ufually called by us the long-legs.

There are a great variety of kinds of the Tipula ; and the frnaller fpecies fo much refemble gnats, that the generality of authors, not excepting evenGoedart and Swammerdam, have confounded the two genera, and defcribed thefe among the gnats. The external appearance, however, is all that con- veys an idea of likenefs between them j for the gnat is fur- nifhed with a trunk, and other ofFenfive weapons, by means of which it is able to pierce our flefh ; and, on the other hand, the Tipula has only a mouth without teeth, and has neither inclination, nor is in a condition to do any harm. It is indeed very happy for us, that this is the cafe, fince the Tipulce are greatly more numerous than the gnats, and were thofe vafl clouds of fmall Tipula, which we fee in marfhy places and elfewhere, and ufually call clouds of gnats, in reality fuch numbers of thofe mifchievous animals, we mould not eafily efcape a good deal of trouble from them. The long form of the body, the pofition of the wings, and the length and pofition of the legs, are the circumftances that make the refemblance between the gnats and Tipula ; but the ftru- cture and organs of the head are alone a very fufficient diftin- ction. All the fpecies of gnats have their origin from water- infects, whofe form they never quit, till they become winded ; but the Tipula are not fo regular, in this refpect; fome of them being produced from water-worms, and others from in- fects of the like form, that have lived on earth, and preyed upon the juices of plants.

As the Tipula differ from the gnats in the figure of the mouth, and in being without a trunk, they differ as much from the other flies of that character, by their refembling the gnat in the fhape of their body. They differ alfo in the conformation of the mouth, and itsfeveral parts and organs. The opening of the mouth is a flit extending itfelf from the fore-part of the head toward the hinder part, and its lips cannot be called up- per and lower ; but they are lateral ones. When the body of the creature is prefled, this mouth opens, and fhews what feem to be a fecond pair of lips within. Thefe are more firmly clofed than the others, and refemble only certain duplications of the flefh. The exterior lips are cartilaginous, and are fur- nifbed with fhort hairs ; the interior are perfectly fmooth, and of a flefhy texture. The head of the Tipula is of a long and flender figure, and is of the nature of thofe which we call the femi- trunk heads, as they much approach to the figure of the trunks of fome other infects. The lips are articulated at the extremity of this head, and on each fide there ftands, on the upper part, a fort of beard, which, when nearly examined, is found to be articulated in the manner of the antennas of in- fects. Thefe two beards, in their ufual pofition, are placed clofe together, and bent forwards over the head : Their office feems to be the covering the aperture of the mouth. Thefe feem conftantly to be found in all fpecies of the Tipula, and placed exactly in the fame manner. They may therefore be ufed as a character of the creature ; and if there fhould be found any fpecies wholly refembling the Tipula, but wanting thefe, it may be very properly called a protipula. Reaumur , Hift. Inf. vol. 9. p. 7.

The larger fpecies of Tipula are ufually found in our meadows, and thefe are in no danger of being confounded with the gnat kind, their fize alone being a fufficient obvious diftinction. Thefe are often found of nearly an inch in length from head to tail ; but their bodies are very flender, and are compofed of only nine rings. The male Tipula is eafily diftinguifhed, at fight, from the female. It is much fhorter in the'body, and is thicker at the tail than any where elfe ; this tail alfo ufually turns upwards, whereas that of the female is placed in the 2 fame