Page:Cyclopaedia, Chambers - Volume 2.djvu/883

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a Plant whofe Flower is faid to follow the Morion of the Sun ; and to turn ftill towards it.

Some fay, 'tis hence it takes its Name, and account for the Effect, by fuppofing that its heavy Stalk, warm'd and foften'd with the Heat which is ftrongeft on that Side toward the Sun, inclines naturally towards the fame ; but others take the Opi- nion to have had its Rife from the Name, which was given it byReafon ofits Appearance in the Time of the greater! Heats, when the Sun is in theTropic.

Some have imagined the Sun-flower of uft in Medicine; but its Reputation that Way is now out of Doors. Its prin- cipal Ufe is in Dying : In order to which, its Juice is infpifla- ted and prepared with Calx and Urine, into blue Cakes ; ufed alio for Starch, inftead of Smalt. See Blue, Smalt, &r.

Its Juice likewife furnilhes the Colour wherewith the People of Zaxgftedoc and fome other Parts of France, where it grows, prepare what they call the Tournefil en "Drapeaux, or Tnrnfol in Rags. The Procefs whereof, is owing to M. Niffole of the Royal Academy of Sciences, and is as follows ;

The Summets or Tops of the Plant being gather'd in the beginning of Augu.fi, are ground in Milk, not unlike our Oil Mills: Then, being put up in Bags, the Juice is exprefs'd with Preffes.

This Juice having been expofed to the Sun about an Hour, they dip Linnen Rags therein, and hang them out in the Air till they be well dried again. When, moiftening them for fome time, over the Vapour of about ten Pound Weight of quick Lime flaked in a fuflicient Quantity of Urine, they lay them out again to the Sun to dry ; to be again dipp'd in the Juice of the Ricionoides.

When they are dried for the laft Time, they are in their Perfection ; and are thus fent into moft Parts of 'Europe, where they are ufed to tin- r e Wines and other Liquors, and give them an agreeable Colour.

The Timet prepare a kind of Ttmifol in Pafte or Cakes, or Stones ; pretended to be the Juice of that Plant Infpiffated : But there is Reafon to think it a Cheat ; and to be the Juice of fome other Plant prepared after the like Manner ; the Tournfol being no Plant of their Growth.

TORPEDO, in Natural Hiftory, a Sea-fi/h, fam'd both among the Ancient and Modern Naturalifts, for a remarkable Numbnefs wherewith it ftrikes the Arm of fuch as touch it.

Various are the Accounts given us of this fingular Fifh ; fome Authors railing the Effects it produces, to a kind of Miracle ; and others treating them as little better than Chi- mera's ; fome folving the Appearance this Way, and fome that. But M. Reaumur, of the French Academy of Sciences, has at length cleared the Point, and fet the Matter in a fa'tis- factory Light.

The Torpedo is a flat Fifli, much of the Figure of the Thorn-back ; fufficiently defcribed in moft Treatifes of Fifh.es, and commonly enough found about the Coafts of 'Provence, Gafiony, &c. where the People eat it without any Danger. See its Figure reprefented in Tab. Natural Hiftory, Fig. 9.

'Phenomenon of the Torpedo.

Upon touching it with the Finger, it frequently, though not always happens, that the Perfon feels an unufual painful Numbnefs, which fuddenly feizes the Arm up to the Elbow, and fometimes to the very Shoulder and Head.

The Pain is of a very particular Species, and not to be defcribed by any Words ; yet Meffieurs Lorenzini, Sorelii, Redi and Reaumur, who all felt it feverally, obferve it to bear fome Refemblance to that painful Senfation felt in the Arm, upon linking the F.lbow violently againft a hard Body : though M. Reaumur aifures us, rhis gives but a very faint Idea thereof.

Its chief Force, is at the Inftant it begins ; it lafts but a few Moments and then vanifhes entirely, If a Man don't actually touch the Torpedo, how near foever he holds his Hand ; he feels nothing : If he touch it with a Stick, he feels a faint Effect : If he touch it through the Interpolition of any pretty thin Body, the_ Numbnefs is felt very confidera- bly ; if the Hand be prefs'd very ftrong againft it, the Numbnefs is the lefs, but ftill ftrong enough to oblige a Man fpeedily to let go.

theory of the Phenomenon of the Torpedo.

There are different Ways of accounting for this Effect : The firft is, that of the Ancients, who contented themfelves with afcribing a Torporific Virtue or Faculty to this Animal.

The fecond, will have this Effect produced by the 'Torpedo, to depend on an Infinity of Corpufcles iffuing continually out of the Fifh, but more copioufly under fome Circumftances than others : This is the Opinion moft generally received j being adopted by Redi, Perrauk and horenzini.

They explain themfelves thus ; As the Fire emits a Quan- tity of Corpufcles, proper to heat us 5 fo the Torpedo emits

a Quantity of Corpufcles fit to numb the Part they infinuate themfelves into ; whether it be by their entering in too great abundance, or by their falling into Tracks or Paflaoes very diiproportionate to their Figures.

The third Account, is that o? Sorelli, who looks on this Emiflron ot Corpufcles, as imaginary: He fays, That upon touching the Fifh, it puts itfelf into a violent Tremor or Agi- tation, and that this becafions a painful Numbnefs in the Hand that touches it But M. Reaumur affures us, That notwith- standing all the Attention he could view this Fifli withal when ready to ftrike the Numbnefs, he could perceive nothing ot this I rcmblmg or Agitation.

The laft and juftert Hypothec's, is that of M. Reaumur : The forpeao, like other flat Fifties, he obferves, is not ab- solutely flat, but its Back, or rather all the upper Part of its Body, a little Convex : When it did not, or would not, pro- duce any Numbnefs in fuch as touch'd it, its Back he found always preferved its natural Convexity; but whenever it would difpofe itfelf to refent a Touch or Thruft, it gradually dimi- nilhed the Convexity of the back Parts of the Body • fome- times only rendring them flat, and fometimes even concave

1 he very next Moment, the Numbnefs always began to faze the Arm ; the Fingers that touch'd, were obli^d to give back, and all the flat and concave Part of the Body was agam feen Convex : And whereas, it only became fiat in- fallibly, it return 'd to its Convexity fo fwiftly, thatonetould not perceive any Paffage from the one to the other State

The Motion of a Ball out of a Musket, is not, perhaps, much quicker than that of the Fifh reaffuming its former Situ- ation ; at leaft the one is not more perceivable than the other. Tis from this fudden Stroke, that the Numbnefs of the Arm arifes ; and accordingly, the Perfon when he begins to led it, imagines that his Fingers have been violenfly°ftruck lis the mere Velocity ot the Stroke that produces the Numb- nefs.

The Wonder is, how fo foft a Subftance, as that of the Fifh, ftiould give fo rude a Blow: Indeed a fingle Stroke of a fort Body could never have done it; But in this Cafe, there is an Infinity of fuch Strokes given in an Inttant. To ex- plain the admirable Mechanifm hereof, we mull give a View of the Parts whereon it depends.

The Mechanifm, then, confifts in two very fingular Muf- cles, b,b, defcribed by feveral Authors, who have given the Anatomy of the Torpedo. Redi, and after him Lorenzini, call them the Mufculi Falcati ; their Form is that of Crefcents and they together, take up almoft Half the Back of the Fifli - the one on the right Side, and the other on the Left Their Origin is a little above the Mouth ; and they are Separated from each other by the Bronchia, into the laft of which they have their Infertion. y

What is fingular in them, is their Fibres ; if, with the Au thors above-mentioned, we may give thatName to a Sort of lef- fer Mufcles as big as Goofes Quills ; of an Affemblage wheteof the two great Mufcles are form'd. Thefe ieffer Mufcles are hol- low Cylinders, their Length nearly equal to the Thicknefs of the Fifh, and ranged a-fide of each other ; all perpendicular to the upper and lower Surfaces of the Fifh, accounting thefe Surfaces as two nearly parallel Planes. The exterior Surface of each of thefe Cylinders, confifts of whitifli Fibres, whofe Direflion is the fame with that of the Cylinder : But thefe Fibres only form a kind of Tube, whole Parietes are not above the Thicknefs of a Leaf of Paper. The Cavity of the Tube is full of a foft Matter, of the Colour and Confidence « "P' dlv ' decl lnto Twenty five or Thirty different little Mafles, by fo many Partitions, parallel to the Safe of the Cylinder ; which Partitions are form'd of tranfverfe Fibres • So that the whole Cylinder is in fome meafure compofed of Twenty five or Thirty fmaller Cylinders placed over each other, and each full of a medullary Subftance.

We need only now, remember, that when the Torpedo is ready to ftrike its Numbne r s, it ftowly flattens the outer Surface of its upper Part; and the whole Mechanifm, where- on its Force depends, will be apparent. By that gradual Con- traftion, it bends, as it were, all its Springs; renders all its Cylinders fhorter, and at the lame time augments their Bafes or, which amounts to the fame, ftretches all the little Inclo- fures which divide the foft Matter. In all Probability too the large Fibres, or little Mufcles, in that Moment, loft their cylindrical Form, to fill the Vacuities between them.

The Contraction being made to a certain Degree, all the Springs unbend ; the longitudinal Fibres are lengthen'd, the tranfverfe ones, or thofe which form the Inclofures, are fhort- en'd; eachlnclofure, drawn by the longitudinal Fibres which are lengthen'd, drives the foft Matter it contains, upwards ; i n which it is apparently affifted by the undulatory Motion which is in the tranfverfe Fibres when contracting.

If then, a Finger touch the Torpedo, it inftantly receives a Stroke, or rather feveral fucceflive Strokes, from each of the Cylinders whereon it is applied. As the foft Matter is diftri- buted into divers Inclofures, 'tis more than probable, all the Strokes are not given precifely at the fame Moment : Nay were there no Inclofures to feparate the Matter, its Impreffion

would