S P I 
S V I 
G;)4 
the sides of which is an equilateral triangle. 
In some cases two opposite sides of the pyra- 
mids are broader than the other two ; and 
sometimes the edges of the octahedron are 
wanting, and narrow faces in their place. For 
figures and descriptions of these, and other 
varieties of these crystals, the reader is re- 
ferred to Rome de Lisle and the abbe Est- 
ner. Lt occurs also in tetrahedrons, in rhom- 
boids whose faces have angles of 120’ and 60’, 
in rhomboidal dodecahedrons, and in four- 
sided prisms terminated by four-sided pyra- 
mids. 
The texture of the spinel is foliated. 
Fracture conchoiclal. Its lustre is 3. Trans- 
parency 2 to 4. It causes a single refraction, 
llardiiess 13. Specific gravity 3.570 to 
3.625. Colour red, of various shades ; some- 
times also blue, green, and yellow. The con- 
stituents of the spinel are, according to 
Vauquelin, ' Klaproth, 
86.00 alumina 76 alumina 
8.50 magnesia 16 silica 
5.25 chromicacid 8 magnesia 
1.5 oxide of iron 
99.76 
101.5 
SPINET, or Sfinnet, a musical instru- 
ment ranked in the second or third place 
among harmonious instruments. 1 he harp- 
sichord is a kind of spinet, only with another 
disposition of thekeys. 
SP1N1FEX, a genus of plants belonging to 
the class of polygamia and order of dioecia. 
The hermaphrodite dowel's have a calyx with 
bivalved biilorous glumes, the valvelets being 
parallel to the raehis ; the corolla is bivalved 
and awnless ; there are three stamina and two 
styles. In the male flowers the calyx is com- 
mon with the hermaphrodite ; the corolla and 
stamina are similar. There is only one spe- 
cies, tlie ‘Squarrosus, a grass of the East 
Indies. 
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 work- 
ing. Hemp, flax, nettle-thread, and other 
like vegetable matters, are to be wetted in 
spinning: silks, wools, See. are spun dry, at 
least they do not stand in need of water : 
there is, however, a way of spinning or reel- 
ing silk as it comes off the cases or balls, 
where hot, and even boiling, water is to be 
used. The vast variety, and importance of 
these branches of our manufactures, 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 occasioned many attempts 
at home to render 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 cot- 
ton, flax, and wool, into yarn. 
SPINSTER, in law. an addition usually 
ygiven to all unmarried women from a vis- 
count’s daughter downwards. 
SPIO, a genus of vermes of the order 
mollusca. The generic character is, body 
projecting from a tube, jointed, and furnished 
with dorsal fibres ; pecluncles or feet rough 
with bristles, and placed towards the back ; 
feelers two, long, simple; eyes two, oblong. 
There are two species, viz. 1. The setiedrn is,' 
which inhabits the ocean where there is a 
clayey bottom, is about three inches long: 
the tube is composed of agglutinated parti- 
cles of earth, thin, erect, and thrice as long as 
the body. From this the animal projects its 
capillary white feelers, in search of food, 
which consists of marine worms. 2. Eili- 
cornis, that inhabits the Greenland sens: tube 
fragile, erect, greenish, from which it pro* 
jects its feelers in search of planariai and 
other small marine worms. 
SPIRACULA, in entomology, holes or 
pores on each side of every segment of the 
abdomen, through which insects breathe. 
SPIREA, a genus of plants belonging to 
the class of icosandria, and to the order of 
pentagynia; and in the natural system ar- 
ranged under the 26th order, pomaceae. The 
calyx is quinquelid; petals five; capsule po- 
lyspermous. There are 22 species ; of which 
two only are British,' the fllipfcndula and ul- 
maria. 
SPIRAL, in geometry, a curve line of the 
circular kind, which, in its progress, recedes 
from its centre. 
A spiral, according to Archimedes, its in- 
ventor, is thus generated: If a right line, as 
All (Plate Miscel. tig. 222), having one end 
fixed, at B, is equally moved round, so as 
with the otlie.r end A to describe the periphery 
of a circle ; and, at the same time, a point is 
conceived to move forward equally from B 
towards A, in the right line BA, so that the 
point describes that line, while the line gene- 
rates the circle: then will the point, with its 
two motions, describe the curve-line B 1,2, 
3, 4, 5, &c. which is called the helix or spiral 
line; and the plane space, contained between 
the spiral line and the right line BA, is called 
the spiral space. 
If also you conceive the point B to move 
twice as slow as the line AB, so that it shall 
get but half-way along the line BA when that 
line shall have formed the circle; and if then 
you imagine a new revolution to be made of 
the line carrying the point, so that they shall 
end their morion at last together ; there will be 
formed a double spiral line, and the two spi- 
ral spaces, as you see in the figure. From 
the genesis of this curve, the following corol- 
laries may be easily drawn. 1. The lines 
Bl2, Bit, B 10, &c. making equal angles 
with the first and second spirals (as also B 12, 
B10, B8, Ike.), are in arithmetical propor- 
tion. 2. The lines B 7, B 10, &c v . drawn 
any how to the first spiral, are to one another 
as the arches of the circle intercepted betwixt 
BA and those lines. 3. Any lines drawn 
from B to the second spiral, as B 18) B 22, &c. 
arc to each other as the aforesaid arches, to- 
gether with the whole periphery added on 
both sides. 4. The first spiral space is to the 
first circle as 1 to 3. And, 5. The first spiral 
line is equal to half the periphery of the first 
circle; for the radii of the sectors, and con- 
sequently the arches, are in a simple arithme- 
tic progression, while the periphery of the 
circle contains as many arches equal to the 
greatest; win refare the periphery to all those 
arches is to ti e spiral lines as 2 to 1. 
Spiral, in architecture and sculpture, im- 
plies a curve that ascends, winding about a cone 
or spire, so that all the points thereof con- 
tinually approach the axis. It is distinguish- 
ed from the helix, by its winding round a 
S P o 
cone, whereas the helix winds in the same 
manner round a cylinder. 
Spirals, proportional, are such spiral 
lines as the rhumb-lines on the terrestrial 
globe; which, because they make equal an- 
gles with every meridian, must also make 
equal angles with the meridians in the stereo- 
graphic projection on the plane of the equa- 
tor ; and therefore will be, as Dr. Hailey ob- 
serves, proportional spirals about the polar 
point. See Rhumb. 
SPIRITS, ardent. See Alcohol. 
SPIRITUALITIES- of a bishop, are the 
profits that he receives as a bishop, and not as 
a baron of parliament; such are the duties of 
his visitation, presentation-money, what arises 
from the ordination and institution of priests) 
the income of his jurisdiction, &c. 
SPIT-INSECT, or Cuckow Spit. See 
Cicada. 
SPLACHNUM, a genus of plants belong- 
ing to the class of cryptogamia, and order of 
musci. The anthem: are cylindrical, and 
grow on a large coloured apophysis or um- 
braculum. The calyptra is caducous. The 
female star grows on a separate stem. There 
are six species, the rubrum, luteum, splnvri- 
cum, ampullaceum, vasculqsum,angustatuni. 
SPITTLE. See Saliva. 
SPLEEN. See A N ATOMY. 
SPLICING, in the sea-language, is the 
untwisting the ends of two cables or ropes, and 
working the several strands into one another 
by a Add, so that they become as strong as if 
they were but one rope, &e. 
SPONDEE, spondenis, in antient poetry, 
a foot consisting of two long syllables, as 
oinnes. Some give the appellation spondaie 
to verses composed wholly of spondees, or at 
least that end with two spondees ; as, 
Constitit, atque oculis Phrygia agmina cir- 
cumspexit. 
SPONDIAS, hog-plum, a genus of the 
decandria pentagynia class of plants, the 
flower of which consists of five ovated, plane, 
and patent petals ; and its fruit is an oval 
berry, containing four nuts in each cell. It is 
called monbin by Plunder. There are four 
species, trees of the West Indies. 
SPONDYLUS, a genus of vermes tes- 
tacea. The generic character is, animal a 
tethys; shell hard, -solid, with unequal valves ; 
one of the valves convex, the other rather 
flat : hinge with two recurved teeth, sepa- 
rated by a small hollow. There are four spe- 
cies. Tlie gcederopus, which has a shell 
slightly cared and spinous, inhabits the Indian 
and other seas, and is found in infinite varieties 
as to size, thickness, and colours; sometimes 
entirely purple, orange, white, or bloom-co- 
lour; sometimes marked with various streaks. 
See Plate Nat. Hist., fig. 373. 
SPONGIA, sponge, in natural history; 
a genus of animals belonging to the class of 
vermes, and order of zoophyta. It is fixed, 
flexible, and very torpid, growing in a variety 
of forms, composed either of reticulated fibres, 
or masses of small spines interwoven together, 
and clothed with a living gelatinous flesh, full of 
small mouths or holes on its surface, by which 
it sucks in and throws out the water. 
Fifty species have already been discovered, 
of which 10 belong to the British coasts. 1, 
Oculata, see Plate Nat. Hist. tig. 374, or 
branched sponge, is; delicately soft and very 
much branched; the branches are a little 
compressed, grow erect, and often united to- 
