40 
A I T 
lower decks, it must follow, that part of the 
air consumed in feeding the fire, must be re- 
spectively drawn out of all such places to 
which the communication shall be so made. 
AIR-PUMP, See Pneumatics. 
AIR SHAFTS, among miners, denote 
holes or apertures let down from the open 
air to meet the adits, and furnish fresh air, 
Sir Robert Murray describes a method, used 
in the coal mines at Liege, of working mines 
without air shafts. When the miners at Men- 
clip have sunk a groove, they will not be at 
the charge of an air shaft till they come at ore ; 
and for the supply of air have boxes of elm 
exactly closed, of about six inches in the clear, 
by which they carry it down about 20 fathom* 
They cut a trench at a little distance from the 
top of the groove, covering it with turf and 
rods disposed to receive the pipe, which they 
contrive to come in sideways to their groove, 
four feet from the top, which carries down 
the air to a great depth. When they come 
at ore, and need an air shaft, they sink it four 
or five fathoms distant, according to the con- 
venience of the breadth, and of the same 
fashion with the groove, to draw as well ore 
as air. 
AIR THREADS, in natural history, a 
name given to the long filaments so frequently 
seen in autumn floating about in the air. These 
threads are the work of spiders, especially of 
that species called the long-legged field 
spider. See Aran e A, 
AIR TRUNK, is a contrivance by Dr. 
Hales to prevent the stagnation of putrid 
effluvia in jails and other places where a great 
number of people are crowded together, in a 
small space. It consists only of a long 
square trunk, open at both ends ; one of which 
is inserted into the ceiling of the room, the 
air of which is required to be kept pure; and 
the other extends a good way beyond the 
roof. The putrid effluvia, therefore, being 
lighter than the pure air of the atmosphere, 
ascend, or are forced by it, through the trunk, 
and carried clear away. The reason why 
vapours of this kind ascend more swiftly 
through a long trunk than a short one, is, that 
the pressure of fluids is always according to 
their different depth, without regard to the 
diameter of their basis, or of the vessel which 
contains them ; and, upon this principle, a 
gallon of water may be made to split a strong 
cask. When the column of putrid effluvia is 
long and narrow, the difference between the 
column of atmosphere pressing on the upper 
end of the trunk, and that which presses on 
the lower end, is much greater than if the 
column of putrid effluvia was- short and wide, 
and consequently the ascent is much swifter. 
One pan of a single pair of scales, which was 
two inches in diameter, being held within one 
of these trunks over the house of commons, 
the force of the ascending air made it rise so 
as to require four grains to restore the equili- 
brium, and this when there was no person in 
the house ; but when it was full, no less than 
12 grains were requisite to restore the equi- 
librium. 
AIR VESSELS are spiral ducts in the 
leaves, &c. of plants, supposed to be analogous 
to the lungs of animals, in supplying the dif- 
ferent parts of a plant with air. S ? ee Physio- 
logy of Plants. 
A1TONIA, (so named in honour of Mr. 
Aiton, his majesty’s gardener at Kew) agenus 
of the class and order monodelphia octandria. 
A K O 
The essential character is, style 1 , cal, four- 
parted, cor- four-petalled ; berry dry, qua- 
drangular, one-celied, many seeded, 
'1 here is but one species, a shrub found at 
the Cape of Good Hope, The segments of 
the calyx and the petals are red, the fruit is 
also red and large. It must Joe kept in a good 
green-house, or a moderate stove, 
A J l GA, Bugle, a genus of the gymno- 
spermia order, and didynamia class ot plants; 
and in the natural method ranking under the 
42d order, Asperifoliaj. The characters are, 
the calyx is a short perianth! inn, monophyllous 
and persistent; the corolla is monopetalous 
and griiming ; the stamina consist of four 
erect subulated filaments ; the antherae are 
dimidiated ; the pistillum lias a four-cleft 
germen, a filiform stylus, and two slender 
stigmata : there is no pericarpium ; the calyx 
converging, and containing the seeds in 'its 
bosom: the seeds are four and oblong. There 
are six species, the principal of which are: 
1. Ajuga genevensis, with woolly leaves 
and hairy cups, a native of Switzerland, and 
of the southern parts of Eur ope. 
2. Ajuga orientals, with inverted 
flowers, is a native of tire East. 
3. Ajuga fyramidalis, or mountain bu- 
gle, with a square pyramidal spike and blue 
llower.s, a native of Sweden, Germany, Swit- 
zerland and England. 
4. Ajuga reptans, common or pasture 
bugle, with creeping suckers, and blue, red, 
or white blossoms, a native of the southern 
parts of Europe, and is met with in woods and 
moist places in many' parts of Britain, The 
roots are astringent, and strike a black colour 
with vitriol of iron. 
AJUTAG E, or Adjutage, a sort of tube, 
fitted to the mouth, or aperture of the vessel, 
through which the water of a fountain is to be 
played, and by it determined into different fi- 
gures. It is indeed chiefly the diversity in 
the ajutages that constitutes the different kinds 
of fountains. And hence, by having several 
adjutages to be supplied occasionally, one 
fountain comes to have the effect of many. See 
Hydraulics. 
AIZOON, a genus of the pentagynia order, 
and icQsandria class of plants, and in the na- 
tural method ranking under (lie 1 3th order, 
succulent;?. The characters are : the calyx 
is a single-leaved perianthium, divided into 
five segments, and persistent: there is no 
corolla : the stamina consist of very numerous 
capillary filaments; the antherae are simple: 
the pistillum has a five-cornered germen 
above, with five simple sty 1 i ; and the stigmata 
are simple: the pericarpium is a bellied, re- 
tuse, five-cornered capsule, having five cells 
and five valves : the seeds are many and glo- 
bular. There are ten species, of which 
1 . Aizoon Canariense, a native of the 
Canary islands ; 
2. Aizoon IIisfanicum, a native of 
Spain; and, 
3. Aizoon Paniculatum, a native of the 
Cape of Good Hope ; are the principal. They 
may all be raised in this country in hot-beds ; 
but they are not remarkable either for beauty 
or any other property. 
AKOND, an oflicer of justice in Persia, 
who takes cognizance of the causes of orphans 
and widows, of contracts and other civil con- 
cerns. He is the head of the school of law, 
and gives lectures to all the subaltern officers. 
He has his deputies in all the courts of the 
A US 
kingdom, who, with the second sadra, make 
all contracts, 
AL, an Arabic particle prefixed to words; 
and signifying much the same with the English 
particle the : thus they say, alkermes, alkuran, 
&c. i, e. the kermes, the Koran, &c. 
ALA, in botany, is used for the hollow of a 
stalk, which either the leaf, or the pedicle of 
the leaf, makes with it ; or it is that hollow 
turning, or sinus, placed between the stalk or 
branch of a plant and the leaf, whence a new 
offspring usually issues. Sometimes it is used 
for those parts yf leaves otherwise called lobes, 
or wings. 
ALABARDA, the name of a spear an- 
ciently used by the Helvetians and Germans. 
ALABAS7 ER, in natural history, a species 
of that genus of stones whose base is calca- 
reous earth. It differs from marble in being 
combined, not with the aerial, but with sul- 
phuric acid; therefore, when mixed with any 
acid, no effervescence appears. It is soluble 
in about 500 times its weight of water at the 
temperature of 60. It is fusible alone in a 
long continued porcelain heat, or by the 
blow-pipe. Specific gravity 1.87. Texture 
granular, with shining particles. In compo- 
sition, and consequently in its chemical pro- 
perties, it does not differ from gypsum, se- 
lenite, or plaster of Paris. The fineness and 
clearness of this stone render it in some mea- 
sure transparent ; whence it has been some- 
times employed for windows. There is a 
church at Florence still illuminated, instead of 
panes of glass, by slabs of alabaster near 1 5 feet 
high, each of which forms a single window, 
through which the light is conveyed. The 
countries in Europe which abound most in 
alabaster are Germany, towards Coblentz; 
the province of Maconnois, in the neighbour- 
hood of Cluni in France; Italy towards 
Rome, where that of Montaiout is particularly 
remarkable not only for its whiteness, but also 
for the size of its blocks, some of which are 
so large, that statues as big as the life may be 
easily cut out of them. A new manufacture 
of basso-relievos, from a singular species of 
factitious alabaster, was some time ago esta- 
blished by Mr. Letapie, at the baths of St- 
Philip in Tuscany. The stream at these 
baths deposits a peculiar kind of sand, which, 
when collected and condensed in the cavities 
of any body employed to oppose its current, 
acquires the nature, hardness, and colour, of 
alabaster, and assumes the forms of those ca- 
vities in which it is thus lodged. There are 
three species of alabaster, viz. 
1. Alabaster, the snow white shin- 
ing, or lygdinum of the antients. 2. The 
variegated, yellow and reddish. This 
species is the common alabaster of the an- 
tients. 3. The yellowish, or phengites of 
Pliny, is found in Greece, Germany, France, 
and Derbyshire in England. The alabasters 
are frequently used by statuaries for small 
statues, vases, and columns. After being cal- 
cined and mixed with water, they may be 
cast in any mould like plaster of Paris. See 
Gypsum and Mineralogy. 
ALT., in anatomy, a term applied to the 
lobes of the liver, the cartilages of the nostril, 
and sometimes to the armpits. 
Al^e, in botany, (the plural of Ala,) is 
used to signify those petals of leaves of pa- 
pilionaceous flowers, placed between those 
others which are called the vexillum and ca- 
rl na, and which form the top and bottom of 
