S I L 
the two threads adhere to each other by that 
gummy quality of which they are pofleflTed. 
The Silk-Worm, previous to fpinning it's web, 
explores foine convenient fituation for ere6ling 
it's cells without obftrudion : and, when it has 
found a chink or leaf adapted to it's piirpole, be- 
gins to wreathe it's head in every direftion ; and 
fallens it's thread on every fide to the verges of 
it's retreat. Though all it's firft effliys feem abun- 
dantly confufed, they are not altogether deftitute 
of defign : there appears, indeed, no order or con- 
trivance in the dil'pofal of it's firft threads ; and 
they are by no means artificially arranged, but 
thrown out a"" random, to ferve as an external fhel- 
ter againft rain for nature having ordained the 
animal to work on trees in the open air, it's habits 
remain, though it be ftieitered in a v^arm apart- 
ment. 
Malpighi pretends to have obferved fix difi'er- 
ent layers in a fingle cone of fiik. But, v/hat may 
cafily be obferved, is, th.it it is externally com- 
pofed of a rough cotton-like fubftance, called flofs : 
within, -the thread is more diftind and even ; and, 
next the body of the aurelia, the apartment feems 
to be lined with a fubftance of the hardnefs of 
paper, but of a much ftronger confiftence. It 
muft not be fuppofcd that the thread which con- 
ftitutesthe cone is roiled round, after the manner 
-of what is called a bottom : on the contrary, it 
lies on it in a very irregular manner; and winds 
off, fometimes from one fide, and fometiines from 
the other. The whole thread will meafure about 
three hundred yards in length; and fuch is it's 
finenefs, that eight or ten of of them are gene- 
rally rolled into one by the manufafturers. The 
cone, when compleated, refembles a pigeon's egg, 
more pointed at one end than the other: at the 
fmaller end the head of the aurelia is generally 
found; and this is the place that the infeft, when 
converted into a moth, is generally obferved to 
perforate. 
The aurelia is commonly a fortnio;ht or three 
weeks in chan^ino; to a moth; but no fooner is 
the winged infe^ft compleatly formed, than having 
diverted itfelf of it's aurelia flcin, it prepares to 
burft through it's cone or external prifon : for this 
purpose it extends it's head towards the point of 
the cone ; butts with it's eyes, which are rough, 
againft the lining of the cell ; gradually wears it 
av/ay ; and at laft puOies forward through a paf- 
fage, fmall at firft, but which enlarges as the ani- 
mal perleveres in it's efforts for emancipation ; 
while the tattered remnants of it's aurelia flcin lie 
confufedly within the cone. 
The animal, thus liberated from it's double con- 
finement, appears as if exhaufted through fatigue; 
and feems to have undergone all this toil and la- 
bour folely for the purpofe of tranlliiitting a fu- 
ture brood. It neither receives food, nor makes 
ufe of it's wings : the male only feeks the female, 
whofe eggs he impregnates ; and their union con- 
tinues for four days without interruption. Im- 
mediarely on the male being feparated from his 
mate, he finiilies his courfe ; and the female fur- 
vives him no longer than till ftie has laid her 
eggs, which lie dormant till the enfuing fpring. 
But though this be the natural progrefs of the 
Silk-Worm, few of thefe animals are fuffered to 
arrive at a ftate of maturity ; for, as their burfting 
through the cone deftroys the Glk, the manufac- 
turers take care to kill the aurelia, by expofing it 
to the fun, before the moth comes to perfedion. 
This done, they remove the flofs, or external coat; 
and then throw the cones into warm water, ftirring 
them aboiit till the firft thread prcfents a clue for 
v/inding all off. Eight of thefe filken threads arc 
generally taken together, the cones being ftill 
kept under v/ater till a proper quantity of the filk 
is v/ound off : however, fome part is left at the 
bottom, on account of it's inferiority in fubftance 
and colour. As to the paper-like fubftance wiuch 
remains at laft, fome ftain it with a variety of co- 
lours, to make artificial flowers ; and othei-s fuffer 
it to lie in the water till the glutinous matter 
which cements it is entirely dilTolved : it is then 
carded like wool, fpun with a wheel, and con- 
verted to feveral ufeful and profitable purpofes. 
SILK-SPIDER. The quality of fpinning filk 
was firft difcovered to be inherent in the Spider 
tribe by M. Bon, in 17 lo. This gentleman ob- 
ferves, that Spiders are diftinguiftied, either with 
regard to their colours, as into black, brown, yel- 
low, white ; or with regard to the numibcr and ar- 
rangement of their eyes ; fome having fix, fome 
eight, and fome ten. But, with regard to Silk- 
Spiders, M. Bon reduces them all into two kinds ; 
thofe with long legs, and thofe with Ihort ; which 
laft furnifh the fineft raw filk. 
The Silk-Spider fpins from the anus, around 
which there are five papillae or fmall nipples, antl 
behind thefe two others; all mufculous, and fur- 
niftied with fphinifters : thefe nipples ferve to form 
and mould a vifcous liquor, which, after being 
dried in the air, becomes filk. Each of thefe nip- 
ples, Reaumur obferves, confifts of a number of 
very minute ones ; but the threads are too fine to 
be counted with exaftitude, though the above- 
mentioned gentleman concludes that each larger 
nipple may fend forth a great many. 
The Spider-bags are of a grey colour v/hen 
new, but turn blackifti on being much expofed 
to the air : they are always lodged in fome fitua- 
tion remote from wind and rain, fuch as hollow 
trees, the corners of windov/s, or under the eaves 
of houfes. By collefting a quantity of thefe bao-s, 
(if we may credit Bon) a new filk is made, in no 
refpeft inferior to the common kind. It ta'Res 
all dyes ; and may be manufaftured into all kinds 
of ftuffs. That gentleman had ftockings and 
gloves made of it, which he prefented to the 
French Academy, as well as to the Royal So- 
ciety of London. 
Reaumur, however, whofe judgment and pe- 
netration as a naturalift have feidom been ex^ 
ceeded, denies, the prafticability of collefting a 
fufficient number of thefe webs to anfwer any be- 
neficial purpofes ; and maintains that the Spiders 
are too untra6lab!e to endure confinement; that 
they deftroy each other; and that their filk is 
neither furniftied in fuch quantities, nor of fuch a 
quality, as to render their breeding and preferva- 
tion worth attention. 
SILPHA. In the Linnsean diftribution, a ge- 
nus of the coleoptera order of infeds: the diftin- 
guifiiing charafters of which are; that the an- 
tenna become thicker towards the extremity; 
the elytra are marginated; the he aci IS prominent; 
and the thorax is flattifn and marginated. Lin- 
naeus enumerates thirty-five fpecies. 
SILVER FISH. This Fifh, which is caught 
near the Cape of Good Hope, is of the fhape of a 
fmall carp, and not very diff^erent in tafte. It is 
of a whitifh colour; and adorned with filver ihin- 
ing ftripes, running tranfverfely from the back to 
the 
