SPl 
from their aspect, show that they have been 
rolled, and also crystallized. Its specific 
gravity is from 3.5 to 3.7. It is unalterable 
before the blow-pipe without addition ; but 
is fusible with borax ; it consists, accord- 
ing to Klaproth, 
Alumina..' 74.5 
Silica 15.5 
Magnesia 8.35 
Oxide of iron 1.50 
Lime 75 
100.5 
Vauquelin gives a somewhat different ana- 
lysis. It is found in the kingdom of Pegu, 
and in the island of Ceylon,accompanied with 
zircon, hyacinth, tourmaline, and ceylanite. 
It is employed as a precious stone, and is of 
considerable value ; but it is not so highly 
esteemed as the oriental ruby : from tliis it 
is distinguished by being harder, and of a 
greater specific gravity. 
SPINET, or Spinnet, a musical instru- 
ment ranked in the second or third place 
among harmonious instruments. See Mu- 
sical Instruments. 
SPINIFEX, in botany, a genus of the 
Polygamia Dioecia class and order. Natu- 
ral order of Gramina, Gramineas, or Gras- 
ses. Essential character: hermaphrodite, 
calyx glume two-valved, two-flowered; 
valves parallel to the rachis ; corolla two- 
valved, awnless; stamens three; styles 
two : male, calyx common with the herma- 
phrodite ; corolla and stamens similar. 
There is only one species ; viz. S. squarro- 
sus, a native of the East Indies, China, and 
Cochinchina, on sandy coasts. 
SPINNING, the act of reducing silk, 
flax, hemp, hair, wool, or other matter, into 
thread. Spinning is either performed on 
the wheel, or with a distaff and spindle, or 
with other machines proper for the several 
kinds of working. Hemp, flax, nettle-thread, 
and other like vegetable matters, are to 
be wetted in spinning : silks, wools, &c. are 
spun dry, at least they do not stand in need 
of water : there is, however, a way of spin- 
ning or reeling silk as it comes off the cases 
or balls, where hot, or even boiling, water 
is to be used. The vast variety and impor- 
tance of these branches of our manufac- 
tures, which are produced from cotton, 
wool, and flax, spun into yarn, together with 
the cheapness of provisions, and the low 
price of labour, in many foreign countries, 
which are the rivals of our trade, have occa- 
sioned many attempts at home to render 
SPI 
spinning more easy, cheap, and expeditious. 
Mr. Arkwright has carried the invention to 
a high degree of perfection. He not only 
contrived methods for spinning cotton, but 
obtained a patent for making cotton, flax, 
and wool, into yarn. See Manufacture 
of Cotton, 
SPINTHERE, in mineralogy, one of the 
earthy fossils, of a greenish colour: it oc- 
curs crystallized, in irregnlar, double, four- 
sided pyramids, which are obliquely trun- 
cated. The crystals are small, and the frac- 
ture foliated. It melts very easily before 
the blow-pipe. 
SPIO, in natural history, a genus of the 
Vermes Mollusca class and, order: body 
projecting from a tube, jointed, and fur- 
nished with dorsal fibres ; peduncles, or feet, 
rough with bristles, and placed towards the 
back ; feelers two, long, simple ; two eyes, 
oblong. There are two species; niz. S. se- 
ticornis : feelers thin and striate : is found 
in the ocean, principally where there is a 
clayey bottom: it is about three inches 
long: the tube is composed of agglutinated 
particles of earth, thin, erect, and thrice as 
long as the body ; from this the animal pro- 
jects its capillary white feelers in search of 
food, which consists of small marine worms : 
body whitish, with a tinge of green, and a 
red line down the middle of the back ; the 
hind part sea-green ; the fore pai t blackish 
grey, with transverse white strim : head pale. 
The other species is S. filicornis : feelers 
thick and annulate: it inhabits the seas 
about Greenland ; it is about an inch long, 
and from its tube projects its feelers in 
search of Planariae, and other small marine 
worms. 
SPIRiEA, in botany, a genus of the Ico- 
sandria Pentagynia class and order. Na- 
tural order of Pomaceae. Rosace®, Jussieu. 
Essential character : calyx five-cleft ; petals 
five ; capsule many-seeded. Tliere are 
twenty-two species. 
SPIRAL, in geometry, a curve line of the 
circular kind, which, in its progress, recedes 
from its centre. 
A spiral, according to Archimedes, its 
inventor, is thus generated : if a right line, 
as A B, (Plate Miscel. XIV. fig. 9) having 
one end fixed at B, be equally moved round, 
so as with the other end A to describe the 
periphery of a circle; and, at the same 
time, a point be conceived to move forward 
equally from B towards A, in the right line 
B A, so as that the point describes that 
line, while the line generates the circle: 
then will tlie point, with its two motions, 
