SPL 
describe the curve line B 1, 3, 4, 6, &c. 
which is called the helix or spiral line ; and 
the plane space contained between the spi- 
ral line and the right line B A is called the 
spiral space. 
It also you conceive the point B to move 
twice as slow as the line A B, so as that it 
shall get but half way along the line B A, 
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 motion at last to- 
gether, there will be formed a double spiral 
line, and the two spiral space.', as you see in 
the figure. From the genesis of this curve, 
the following corollaries may be easily 
drawn. 1. The lines B 12, B 11, B 10, 
&c. making equal angles with the first and 
second spiral (as also B 12, B 10, B 8, &c.) 
are in arithmetical proportion. 2. The lines 
B 7, B 10, &c. drawn any how to the first 
spiral, are to one another as the arches of 
the circle intercepted between B A and 
those lines. 3. Any lines drawn from B to 
the second spiral, as B 18, B 22, &c. are to 
each other as the aforesaid arches, together 
with the whole periphery added on both 
sides. 4. The first spiral space is to the 
first circle as one to 3. And, 5, The first 
spiral line is equal to half the periphery of 
the first circle; for the radii of the sec- 
tors, and consequently the arches, are in a 
simple arithmetical progression, while the 
peripher 3 ' of the circle contains as many 
arches equal to the greatest ; wherefore the 
periphery to all those arches is to the spiral 
lines as 2 to 1. 
Spiral, in architecture and sculpture, 
implies a curve that ascends, winding about 
a cone or spire, so as all the points thereof 
continually approach the axis. It is distin- 
guished from the helix, by its winding 
around a cone, whereas the helix winds in 
the same manner around a cylinder. 
Spirals, proportional, are such spiral 
lines as the rhumb lines on the terrestrial 
globe, which, because they make equal 
angles with every meridian, must also make 
equal angles with the meridians in the ste- 
reographic projection on the plane of the 
equator ; and therefore will be, as Dr. Hal- 
ley observes, proportional spirals about the 
polar point. 
SPIRE, in architecture, was used by 
the ancients for the base of a column,, and 
sometimes for the astragal, or tore. But, 
among the modems, it denotes a steeple 
that continually diminishes as it ascends, 
whether conically or pyramidallj’. , 
SPO 
SPLACHNUM, in botany, a genus of 
the Cryptogamia Mrsci class and order. 
Generic character: capsule cylindrical; 
veil and receptacle very large ; fringe with 
eight teeth. Male, a bud on a different 
plant; circular, terminating. 
SPLEEN. See Anatomy. 
SPLENTS, or Splints, in surgery, 
pieces of wood, used in binding up broken 
limbs. 
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- fidd, so that they become as 
strong as if they were but one rope. 
SPLINTER, a small shiver of wood, or 
the like. The splinters of fractured bones, 
if loose, are to be carefully removed, other- 
wise replaced. 
SPODUMENE, in mineralogy, one of 
the earthy fossils, of a greenish- white colour, 
passing into apple-green. It occurs in small 
masses, is .shining, and of a pearlj' lustre. 
Specific gravity about 3.2. It splits before 
the blow pipe into smallish yellowish folia, 
and at length melts into a greyish white 
transparent glass. It is found in the mines 
of Upton, in Sweden, accompanied with 
quartz >and black mica. 
SPONDEE, spondcEus, in ancient poetry, 
a foot consisting of two long syllables, as 
omnes. 
Some give the appellation spondaic to 
verses composed wholly of spondees, or at 
least that end with two spondees ; as, 
Constitit, atque oculus Phrygia agtnina dr- 
cumspexit, 
SPONDIAS, in botany, hog-plum, a ge- 
nus of the Decandria Pentagynia class and 
order. Natural , order of Terebintaceas, 
Jussieu. Essential character: calyx five- 
toothed; corolla five-petalled ; drupe with 
a five-celled nut. There are four species. 
SPONDYLUS, in natural history, a ge- 
nus of the Vermes Testacea class and order : 
animal a tethys : shell hard, solid, with un- 
equal valves; on© of the valves convex, the 
other rather flat : hinge with two recurved 
teeth, separated by a small hollow. There 
are four species : the shell of the S. gaedaro- 
pns is slightly eared, and spinpus : it inha- 
bits the Mediterranean, Indian, and other 
seas, and is found in almost infinite varieties 
as to size, thickness, and colours ; some- 
times entirely purple, orange, white, or 
bloom colour; sometimes marked with va- 
rious streaks, spots, dots, or bands. 
SPONGIA, in natural history, sponge, a 
genus of the Vermes Zooelivta class and 
PS 
