asc 
the latitude of the place, so is the tangent 
of the sun's declination to the sine of the 
ascensional difference; by subtracting of 
which from the right ascension, when the 
sun is in the northern signs, and adding it, 
when the sun is in the southern ones, ) ou 
will find the oblique ascension. 
ASCENT of fluids is particularly under- 
stood of their rising above their own level, 
between the surfaces of nearly contiguous 
bodies, or in slender capillary glass tubes, 
or in vessels filled with sand, ashes, or the 
like porous substances. This effect happens 
as well in vacuo as in the open air, and in 
crooked as well as straight tubes. Some 
liquors, as spirit of wine and oil of turpen- 
tine, ascend with greater celerity than 
others ; and some rise after a different man- 
ner from others. Mercury does not ascend 
at all, but rather subsides. Upon the same 
principle, two smooth polished plates of 
glass, metal, stone, or other matter, being so 
disposed as to be almost contiguous, have 
the effect of several parallel capillary tubes ; 
and the fluid rises in them accordingly: the 
like may be said of a vessel filled with sand, 
&c. the divers little interstices of which form 
as it were a kind of capillary tubes : so that 
the same principle accounts for the appear- 
ance in them all. And to the same may 
probably be ascribed the ascent of the sap in 
vegetables. Thus Sir I. Newton says, if a 
large pipe of glass be filled with sifted ashes, 
well pressed together, and one end dipped 
into stagnant water, the fluid will ascend 
slowly in the ashes, so as in the space of a 
week or fortnight to reach the height of 30 
or 40 inches above tire stagnant water. This 
ascent is wholly owing to the action of those 
particles of the ashes which are upon the 
surface of the elevated water ; those within 
the water attracting as much downwards as 
upwards : it follows, that the action of such 
particles is very strong ; though being less 
dense and close than those of the glass, their 
action is not equal to that of glass, which 
keeps quicksilver suspended to the height of 
,60 or 70 inches, and therefore acts with a 
force which would keep water suspended 
to the height of about 60 feet. By the same 
principle a sponge sucks in water; and the 
glands in the bodies of animals, according 
to their several natures and dispositions, im- 
bibe various juices from the blood. If a 
drop of oil, water, or other fluid, be laid on 
a glass plane, perpendicular to the horizon, 
so as to stand without breaking or running 
off, and another plane inclined to the for- 
pier so as to meet at top, be brought to touch 
ASC 
the drop, then will the drop break, and 
ascend towards the touching end of the 
planes ; and it will ascend the faster in pro- 
portion as it is higher, because the distance 
between the planes is constantly decreasing. 
After the same manner the drop may be 
brought to any part of the planes, either up- 
ward, or downward, or sideways, by altering 
the angle of inclination. Lastly, if the 
same perpendicular planes be so placed as 
that two of their sides meet, and form a 
small angle, the other two only being kept 
apart by the interposition of some thin body, 
and thus immerged in a fluid tinged with 
some colour ; the fluid will ascend between 
the planes, and this the highest where the 
planes are nearest, so as to form a curve 
line, which is found to be a just hyperbola, 
one of the asymptotes whereof is the line 
of the fluid, the other being a line drawn 
along the touching sides. The physical 
cause in all these phenomena is the same 
power of attraction. 
ASCIDIA, in natural history, a genus of 
worms, of the order Mollusca. Body fixed, 
roundish, and apparently issuing from a 
sheath: two apertures, generally placed 
near the upper end, one beneath the other. 
There are more than 40 species found in the 
sea, adhering by their base to rocks, shells, 
and other submarine substances. They are 
more or less gelatinous, and have the power 
of squirting out the water which they take 
in. Some of them are esculent: most of 
them sessile, though a few are furnished 
with a long stalk, or tubular stem. They 
alternately contract and dilate them- 
selves. 
ASCII, among geographers, an appella- 
tion given to those inhabitants of the earth, 
who, at certain seasons of the year have no 
shadow: such are all the inhabitants of 
the torrid zone, when the sun is vertical to 
them. 
ASCIUM, in botany, a genus of the Poly- 
andria Monogynia class and order. Charac- 
ter : calyx five-leaved ; petals five ; berry 
four-celled, with two seeds in each. One 
species in Guiana, a tree 80 feet high. 
ASCLEPIAS, swallow-wort , in botany, a 
genus of the Pentandria Digynia class of 
plants, the calyx of which is a permanent 
perianthium, divided into five acute and 
small segments ; the corolla consists of a 
single petal, divided into five deep segments 
at the mouth; and its fruit consists of two 
follicles or vaginae, containing a great num- 
ber of imbricated seeds, winged with down- 
There are about 40 species. The swallow* 
