ALT 
A L T 
ALU 
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per AT pi vi us, a famous- botaiiist. It is a na- 
tive of the West Indies. It is with us treated 
as a stove aquatic. 
ALQUIER, a liquid measure used in Por- 
tugal to measure oil, two of which make an 
almond. 
aLQUIFORK is a sort of mineral lead, 
very heavy, easily reduced to powder, and 
difficult to fuse. The potters use it to give 
their works a green varnish. It is found in 
Cornwall, and called potter’s ore. it con- 
tains probably some mixture of cobalt. 
ABEAM ECU , in astronomy, the name of 
a star of the lirst magnitude, otherwise called 
arcturus. 
ALSINE, chickweed, the name of a 
genus of plants, of the class and order of pen- 
tandria trigvnia. I'he corolla is live equal 
petals, which, with the five-leaved calyx aiiu 
a capsule oue-ceiled, three-valved, form the 
essential character. Happily for gardeners 
there are but three species of this vile weed, 
and but one in England. This however, 
though an annual, affords sufficient trouble. 
It appears to be of no use whatever, though 
it is called chickweed, from the notion that 
chickens feed on it, which must be when they 
can get nothing else. 
ALSIRAT, in the Mahometan theology, 
denotes a bridge laid over the middle of 
•hell, the passage or path whereof is sharper 
than the edge of a sword ; over which, how- 
ever, every soul must pass at the day of judg- 
ment, when the wicked will tumble headlong 
into hell, whereas the good will fly over it. 
ALSTON IA, a genus of the polyandria 
monogynia class and order. The corolla is 
shorter than the calyx ; and the essential 
character is, corolla one-petalled, eight or 
ten cleft ; the clefts alternated. There is only 
one species, a shrub of South America, the 
leaves of which are said to have the taste of tea. 
A LSTR O E M ER 1 A , a genus of plants of 
the hexandria monogynia class and order, and 
of the natural order ot lilia. The essential cha- 
racter is, corolla six petals, subbilabiate ; the 
two lower petals tuhulose at the base ; sta- 
mina bending down. 
There are six species, all natives of South 
America. They are cultivated here as orna- 
mental plants. The A. pelegrina and ligtu 
are the most beautiful and the most common. 
T he former will bear to be treated as a green- 
house plant, and some assert that it thrives 
best even in a garden frame. 
ALTAR-THANE, in our old law books, 
an appellation given to the priest, or parson 
of a parish, to whom the altarage belonged. 
. ALTARAGE, among ecclesiastical wri- 
ters, denotes the profits arising to a priest on 
account of the altar, as well as the offerings 
themselves made upon it. 
ALTERANTS, or Alterative medi- 
cines, in pharmacy, such medicines as are 
supposed to correct the bad qualities of tiie 
blood and other animal fluids, without occa- 
sioning any sensible evacuation. 
ALTERN Base, in trigonometry, a term 
used in contradistinction to the true base. 
Thus, in oblique triangles, the true base is 
either the sum of the sides, and then the dif- 
ference of the sides is called the alternbase; 
or the true base is the difference of the sides, 
and then the sum of the sides is called the al- 
tera base. 
ALT ERNATE, in heraldry, is said in re- 
spect. of the situation of the quarters. 
T hus the first and fourth quarters, and the 
second and third, are usually of the same na- 
ture, and are railed alternate quarters, 
Alternate, such a disposition of the leaves 
of a plant, that the first on one side of a 
branch stands higher than tiie first on the 
other side, the second the same, and so on 
to the top. 
Alternate allegation. See Arith- 
metic. 
Alternate angles. See Geometry. 
ALTiE'EA, Marsh-mallow, a genus 
of plants, with a double calyx, the exterior 
one being divided into nine segments ; the 
fruit consists of numerous capsules, each con- 
taining a single seed. It belongs to the mo- 
nadelphia polyandria class of Linnaaus. The 
essential character is, calyx double, outer 
nine-cleft ; arils many, one-seeded. 
There are seven species, of which the A. 
officinalis, or common marsh-mallow, is well 
known. It was formerly supposed to possess 
many medical virtues, but is now scarcely 
used in any preparation whatever. The 
flowers and seed are nearly the same with 
those of the malva, or mallow. 
ALT1N, in commerce, a kind of money 
current in Muscovy, worth three copies. 
ALTITUDE, in geometry, one of the 
three dimensions of body ; being the same 
with what is otherwise called height. 
Altitude of a figure, is the nearest dis- 
tance of its vertex from its base, or the 
length of a perpendicular let fall from the 
vertex to tiie base. 
Altitude, in optics, is the height of an 
object above a line, drawn parallel to the 
horizon from the eye of the observer, or the 
angle subtended between a line drawn 
through the eye parallel to the horizon, and a 
visual ray emitted from an object to the eye. 
See Optics. 
Altitude of the eye, in perspective, is 
its perpendicular height above the geometri- 
cal plane. 
Altitude of a star, fc. in astronomy, is 
an arch of a vertical circle, intercepted be- 
tween the star and the horizon. 
This altitude is either true or apparent, 
according as it is reckoned from the rational 
or sensible horizon, and tiie difference be- 
tween these is what is called by astronomers 
the parallax of altitude. 
The true altitudes of the sun and fixed 
stars differ but little from their apparent alti- 
tudes, because of their great distance from 
the earth, and the smallness of the earth’s 
semi-diameter compared with it. r l he quan- 
tity of refraction is different at different alti- 
tudes, and the parallax is different, according 
to tiie distance of celestial objects ; in the 
fixed stars it is too small to be observed with 
any degree of certainty : that of the sun is 
about S-~ sec. and that of tiie moon 52 min. 
Sailors commonly take the altitude of stars 
with a quadrant, but as this method is liable 
to an error of six, seven, or more minutes, 
from the motion of the ship, as well as the 
coarseness of their instruments, Mr. Parent lias 
given a new way of finding their altitudes, by 
means of a common watch. 11 is method is 
this : having observed the difference of time 
between the rising of two stars, the right as- 
cension and declination of which are known 
from astronomical tables, in the Nautical Al- 
manac, it will be easy to distinguish that part 
of tiie difference which arises from that diffe- 
rent position, from that arising from the obli- 
quity of the sphere. N ow this last is precisely 
the altitude of the pole of the place of obser- 
vation ; for as to the way the ship may have 
made between the rising of the two stars, it is 
so small as to be safely overlooked, or at most 
estimated in the common way of reckoning. 
The ship changing place between the two 
observations, renders this method liable to 
some objection ; but the small alteration 
either of the ship’s longitude or latitude will 
make no sensible -error, and if she happens to 
have run a good distance between tiie obser- 
vations, it is easy reckoning how much it 
is, and accordingly allowingfor it. See Navi- 
gation. 
Altitude, accessible, &c. See Trigo- 
nometry. See also Gnomon, Pin, Qua- 
drant, &c. 
Altitude refraction of, is an arc of a 
vertical circle, by which the altitude of a hea- 
venly body is increased by means of refrac- 
tion. This is different at different altitudes, 
being nothing at the zenith, and greatest at 
the horizon. 
Altitude, parallax of, the difference be- 
tween the true and apparent place of a star : it 
diminishes the altitude of the star, or increases 
its distance from the zenith. 
Altitude of motion, according to Dr. 
\V aliis, is its measure estimated in the line of 
direction of tiie moving force. 
Altitude, determinative, that whence a 
heavy body falling, acquires a certain velocity 
by its natural acceleration. 
ALTO-RELIEVO. See Relievo. 
ALTO RIPIENO, in music, the tenor of 
the great chorus which sings or plays only now 
and then in some particular places. 
ALVARID, in the history of Spain, a kind 
of magistrate or judge, differing very little from 
the alcaid. ' 
ALVARISTS, a branch of thomists, so 
called from Alvares their leader; who as- 
serted sufficient grace, instead of the effica- 
cious grace of the antient thomists. 
ALU DE, a kind of sheep’s leather, one side 
of which has the wool on. 
A LU DELS, in chemistry, are earthen pots 
ranged one above another, for retaining the 
products which ascend in tiie process of subli- 
mation. 
The lowest aludel is fitted to a pot, placed in 
the furnace, in which is the matter, to be sub- 
limed ; and at top is a close head to retain the 
sublimates which ascend highest. 
ALVEARIUM, among anatomists, de- 
notes the hollow of the auricle, or outer ear. 
ALVEHEZ1T, denotes, among Arabian 
writers, what we call falling-stars. 
ALVEOLATE, in botany, a term used in 
the same sense as honey-combed, to express 
something that is fun-owed by oblong depres- 
sions. ’ 
ALVEOLUS, in. anatomy, the socket-like 
cavity in the jaws, wherein each of the teeth 
is fixed. 
Alveolus, in the history of fossils, a ma- 
rine body, not known at present in its recent 
state, but frequently found fossile. 
'I he alveoli are of a conic shape, and com- 
posed of a number of cells, like so many bee- 
hives, jointed into one another, with a pipe of 
communication, like that of the nautilus. 
They are sometimes met with entire, but 
more frequently truncated, or with their 
smaller ends broken off. 
ALULA notha, bastard or spurious 
wing, in ornithology, is a kind of appendage 
to the true and principal wing, placed near its 
