Page:Cyclopaedia, Chambers - Volume 1.djvu/618

 DUG

[ 252 ]

DUE

of 'em us'q in Plumes on Childrens Heads, and divers other Works, much finer than any Hair ; and which bend, and wave like them with every Wind.

Nothing is more fimple and cafy than the Method of making tjiem : There are two Workmen employ'd : The firft holds one End of a Piece of Glafs o\cr the Flame of a Lamp ; and when the Heat has foften'd it, a fecond Workman applies a Glafs-hook to the Metal thus in Fufion; and withdrawing the Hook again, it brings with it a Thread ofGlafs^ which ftitt adheres to the Mafs. Then, String his Hook on the Circumference of a Wheel about a Feet and a half in Diameter, he turns the Wheel as faft as hepleafes- which drawing out the Threads, winds it on its Rim - till after a certain Number of Revolutions it is cover'd with a Skain of Glafs-Thread.

The Mafs in Fufion over the Lamp, diminlfhes infcnfibly, ■■■:n:(z wound out, as it were, like aPelotoon, or Clue upon the Wheel ; and the Parts, as they recede from the Flame, cooling, become more coherent with thofe next to 'em ; and this by Degrees : The Parts neareft the Fire, are always the leafl connected together, and of Confequence muft give Way to the Effort the reft make to draw 'em towards the Wheel.

The Contour of thefe Threads is ufually a flat Oval, be- ins three or four times as broad as thick. Some of 'em fcarce fecm bigger than the Thread of a Si Ik- Worm 5 and are flexible to a Miracle. If the two Ends of fuch Threads be knotted together, they may be drawn and bent, till the Aperture, or Space in the Middle of the Knot don't exceed one 4th of a Line, or one 48th of an Inch in Diameter.

Hence, Mr. Reaumur advances, that as the Flexibility of Glafs increafes in Proportion to the Finenefs of the Threads; had we but the Art of drawing Threads as fine as thole of a Spider's Web, we might weave Stuffs, and Cloaths here- of, for Wear.

Mr. Reaumur made fomc Experiments this Way : He could make Threads fine enough, as fine, in his Judgment, as any Spider's web, but could never make 'em long enough, to do any Thing with 'em.

The fame ingenious Author obferves, that theMatter where- of Spiders and Silk-worms form theirThreads, is brittle, when in the Mafs, like dry Gums. As 'tis drawn out of their Bodies, it afTumes a Confidence, much as Glafs-threads be- come hard, as they recede from the Lamp; tho' from a diffe- rent Caufe. The 2)u£tility of this Matter, and the Appara- tus thereto being much more extraordinary in Spiders, than in Silk-worms ; we fhall here only confider the former. Something has already been faid of each under the Article Silk, which fee.

Near the Anus of the Spider are 6.x Papilla, or Teats, reprefented in Tab. Nat. Hifiory Fig. 6. The Extremities of the &vcxa\Papillee are turnifh'd with Holes, that do theBufi- nefs ofWiar-drawers, in forming the Threads. Of thefe Holes, M.. Reaumur obferves, there are enough in theCompafs of the fmalleft Pins-head, to yield a prodigious Quantity of diflincf Threads. The Holes are perceiv'd by their Effects : Take a large Garden-Spider ready to lay its Eggs, and applying the Finger on a Part of its Papilla, as you withdraw that Finger, it will take with it an amazing Quantity of diffe- rent Threads.

Monfr. Reaumur has often told 70, or So, with a Micro- scope, but has perceiv'd, that there were infinitely more than he could tell. In effect, if he fhould fay, that each Tip of a Ta^illa furnifh'd a thoufand, he is perfuaded, he fhould fay vaftly too little. The Part is divided into an In- finity of little Prominences, like the Eyes of a Butter-fly, &c. Each Prominence, no doubt, makes its feveral Thread ; or rather, between the feveral Protuberances, are Holes that give Vent to Threads ;' the TJfe of the Protuberances, in all probability, being to keep the Threads at their firft Exit, ere yet harden'cl by the Air, a-part. In fome Spiders thefe Protuberances are «. not fo lenfible; but in lieu thereof there are Tufts of Hair, which may ferve the fame Office, viz. to keep the Threads a-part. Be this as it will, there may Threads come out at above a thoufand different Places in every Papilla ; confequently, the Spider having fix Pa- pill<£, has Holes for above tfoco Threads. 'Tis not enough, that thefe Apertures are not only immenfely fmall: The Threads are already form'd 'ere they arrive at the Papilla, each of 'em having its little Sheath, or Duel, in which it is brought to the 'Papilla from a good Diftance.

Monfr. Reammir traces 'em up to their Source, and fhews the Mechanifm by which they are made. Near the Origin of the Belly, he finds two little foft Bodies, which are the firft Source of the Silk. Their Form and Tranfparency re- femble thofe of Glafs-bcads, (feeiv^.7.) by which Name we mail hereafter denote them. The Tip of each Bead, as R, goes winding, and makes an Infinity of Turns, and Re- turns towards the 'Papilla. From the Bafe, or Root of the Bead, proceeds another Branch much thicker ; which wind- ing variously, forms feveral Knots 3 and takes its Courfe like

the other, towards the Hind-part of the Spjder. In thefe Beads, and their Branches, is contain'd a Matter proper to form the Silk, only that it is too foft. The Body of the Bead is a Kind of Refervoir, and the two Branches two Ca- nals proceeding from it. A little further backward, there are two other TetTer Beads, which only fend forth one Branch a-piece, and that from the Tip. Befide thefe, there are three other larger "VeiTels on each Side the Spider, which Mr. Reau- mur takes for the laft Refervoir, where the Liquor is col- lected. They are reprefented (Fig.S.) The biggeft is near the Head of the Infect, and the leaft near the Anus. They all terminate in a Point ; and from the three Points of thefe three Refervoirs it is, that the Threads, at leaft the greater} Part of the Threads, drawn out at the three 'Papillae, proceed. Each Refervoir fupplies one Papilla. Laftly, at the Roots of the PapilleS, arc difcern'd feveral flefhy Tubes : probably, as many as there are Papillce. Upon lifting up the Mem- brane, or Pellicle, that feems to cover thefe Tubes, they ap- pear full ofThreads, all diftincf. from each other, and which, of Confequence, under a common Cover, have each their par- ticular One 5 being kept like Knives in Sheaths. The im- menfe Quantity ofThreads contain'd here, Monfr. Reau- mur concludes, upon tracing their Courfe, do not all come from the Points of the Refervoirs ; but fome from all the Turns, and Angles; nay probably, from every part thereof. But by what Conveyances the Liquor comes into the Beads, and out of the Beads into the Refervoirs, remains yet to be difcover'd.

We have already obferv'd, that the Tip of each Papilla- may give Paffage to above a thoufand Threads ; yet the Diameter of that Papilla does not exceed a fmall Pins-head; But we were there only confidering the largeft Spiders.

If we examine the young, rifing Spiders, produced by thofe ; we fhall find, that they no fooncr quit their Egg, than they begin to fpin. Indeed their Threads can fcarce be per- ceiv'd ; but their Webs, form'd thereof, may. They are fre- quently as thick, and clofe, as thofe of Houfe-Spiders ; And no Wonder: there being often 4, or 500 little Spiders concur- ing to the fame Work. How minute muft their Holes be? The Imagination can fcarce conceive that of their Papilla, The whole Spider is perhaps Itfs than a Papilla of that which produced it.

This is eafily feen : Each big Spider lays 4 or 500 Eggs^ thefe Eggs are all wrapp'd up in a Bag ; and as foon as the young Ones have broke through the Bag, they begin to fpin. How fine muft their Threads be ?

Tet is not this the utmoft Nature does : There are fome Kinds of Spiders fo fmall at their Birth, that they are not vifible without a Microfcopc. There are ufually found an Infinity of 'em in aClufler, and they only appear likea Num- ber of red Points. And yet there are Webs found under them, tho' well nigh imperceptible. What muft be the Te- nuity of one of thefe Threads? The fmalleft Hair muft be to one of thefe what the moft maflive Bar is to the fineft Gold-wiar above mentioned.

The Matter whereof the Threads arc form'd, we have ob- ierved, is a vifcid Matter. The Beads are the firft Recep- tacles where it is gather'd, and the Place where it has the leaft Confiftence. 'Tis much harder when got into the fix great Reiervoirs, whither 'tis carried by Canals from the former : Tins Confiftence it acquires in good Meafure in its PafTage ; Part oi the Humidity being diffipated in the Way ; or fe- paratLd by Pi:rts deftined for that Purpofe.

Laftly, the Liquor is dried frill further, and becomes Thread, in its Ptogrefs through the refpecfivc Canals to the PapiUcff. When thefe firft appear out at the Holes, they are ftill glutinous ; fo that fuch' as Poring out of neighbouring Holes, flick together. The Air compleats the drying.

By boiling the Spider, more, or lefs, the Liquor is brought to a greater or Ic.fs Confiftence, fit to draw out into Threads, for 'tis too fluid for that Purpoie, while yet inclofed in itsRe- fervoirs.

The Matter contain'd in thefe Refervoirs, when well dried, appears a tranfp^rer.t Gum, or Glue, which breaks when much bent : Like Glafs, it only becomes flexible by being divided into the fineft Threads. And probably 'twas on this Account Nature made the Number of Holes fo immenfe. TheMat- ter of the Silk form'd in the Bodies of Spiders being much brittler than that form'd in Silk-worms, needed to be wound fmaller. Otherwife we don't conceive, why fhe fhould form a great Number ofThreads, which were afterwards to be re- united : a fingle Canal might have don 1. 1 . See Divisibi- lity.

DUEL, a fingle Combat, at a Time and Place appointed, in Confequence of a Cartel, or Challenge. SeeCn allenge,^.

1)ueh were anciently allowed by common Law, in Cafes where Proof could not be had. In which Senfe Fleta de- fines 2)uel t Singulars Pug?za inter duos ad probandam Veritatem Litis, ££ qui vicit, probajje intelligitur. Stat, de Finib. Levat, 27. EdllX See Combat.

This