A X I 
line, the magnet will then be cut into two loadftones. And 
the extremities of fuch lines are called the poles of the done. 
Axis, in mechanics. The axis of a balance, is the line 
Upon which it moves or turns. 
Axis of Oscillation, is a line parallel to the hori¬ 
zon, palling through the centre about which a pendulum vi¬ 
brates, and perpendicular to the plane in which itofcillates. 
Axis in Peritrochio, or wheel and axle, is one of the 
five mechanical powers, or Ample machines; contrived 
chiefly for the railing of weights to a conliderable height, 
as water from a well, &c. This machine confifts of a cir¬ 
cle A B, concentric with the bafe of a cylinder, and move¬ 
able together with it 
about its axis C D. 
This cylinder is called 
the axis ; and the cir¬ 
cle, the peritrockium ; 
and the radii, or 
fpokes, which are 
fometimes fitted im¬ 
mediately into the cy¬ 
linder, without any 
circle, the fcytalx. 
About the axis winds 
a rope, or chain, by 
means of which great 
weights are raifed by turning the wheel. The axis in pe¬ 
ritrochio takes place in the motion of every machine, in 
which a circle may be conceived as deferibed about a fix¬ 
ed axis, concentric with the plane of a cylinder about 
which it is placed ; as in crane-wheels, mill-wheels, .cap- 
flans, See. The chief properties of the axis in peritro¬ 
chio, are as follow : i. If the power F applied in the di¬ 
rection AFa tangent to the circumference, or perpendi¬ 
cular to the fpoke, be to a weight E, as the radius of the 
axis Ce is to the radius of the wheel A D, or the length 
of the fpoke; the power will juft fuftain the weight; that 
is, the power and the weight will be in equilibrio, when 
they are in the reciprocal proportion of their diftances 
from the centre. 2. When the wheel moves, with the 
power and weight; the velocities of their motion, and the 
Ipaces pafled over by them, will be both in the fame pro¬ 
portion as above, namely, direCtly proportional to their 
diftances from the centre, and reciprocally proportional to 
their own weights when they are in equilibrio. 3. A pow¬ 
er and a weight being given, to conftruCt an axis in peri¬ 
trochio, by which it (hall be fuftained and raifed : Let the 
axis be taken large enough to fupport the weight and pow¬ 
er without breaking : then, as the weight is to the power, 
f'o make the radius of the wheel to the radius of the axis. 
Hence, if the power be very fmall in refpect of the weight, 
the radius of the wheel will be vaftly great. For exam¬ 
ple, fuppofe the weight 4050, and the power only 50; then 
the radius of the wheel will be 81 times that of the axis; 
which would be a very inconvenient (ize. But this incon¬ 
venience is provided againft by increafing the number of 
the wheels and axes; making one to turn another,by means 
of teeth or pinions. And, to find the effeCl of a number 
of wheels and axes, thus turning one another, multiply to¬ 
gether all the radii of the axes, and all the radii of the 
wheels, and then it will be, as the product of the former 
is to the product of the latter, fo is the power to the weight. 
So, if there be 4 wheels and axes, the radius of each axis 
being 1 foot, and the radius of each wheel 3 feet; then 
the continual produC .1 of all the wheels is 3 X 3 X 3 Xt> or 
81 feet, and that of the axis only 1; therefore the eft'eCt 
is as 81 to 1, or the weight is 81 times the power. And, 
on the contrary, if it be required to find the diameter of 
each of four equal whee’s, by which a weight of 40501b. 
ft) all be balanced by a power of 501b. the diameter of each 
axis being one foot: dividing 4050 by 50, the quotient is ' 
Si; extraCl the fourth root of 81, or twice the fquare 
root, and it will give 3, for the diameter of the four wheels 
fought. 
Axis of a Vessel, is that quiefeent right line palling 
Vol. II. No. 90. 
A X Y 
585 
through the middle of it, perpendicular to its bafe, and 
equally diftant from its (ides. 
Axis, in optics. Optic axis, or vifual axis, is a ray paf- 
fing through the centre of the eye, or falling perpendicu¬ 
larly on the eye. 
Axis of a Lens, or Glass, is the axis of the folid of 
which the lens is a fegment. Or the axis of a glafs, is the 
line joining the two vertices or middle points of the two 
oppofite furfaces of the glafs. . 
Axis of Incidence, in dioptrics, is the line palling 
through the point of incidence, perpendicularly to the re¬ 
fracting furface. 
Axis of Refraction, is the line continued from the 
point of incidence or refraCtion, perpendicularly to the re- 
' trading furface, along the farther medium. 
AX'LE, or Axle-tree, f. [axis, Lat.] The pin which 
palfes through the midft of the wheel, on which the cir¬ 
cumvolutions of the wheel are performed.—The fly fat 
upon the axle-tree of the chariot-wheel, and faid, What a 
dull do I raife! Bacon. 
AX'MINSTER, a market-town in Devonfliire, 15* 
miles from London, lixty from Bath and Briftol, twenty- 
five from Exeter, twenty-three from Taunton, and five 
from the Britifti Channel. It takes one part of its name 
from the river Ax, near which it (lands, and the other 
from a minder, ereCted by king Athelftan, for feven priefts 
to pray for the departed fouls of fome perfons buried here, 
who were killed in his army, when he defeated the Danes 
in a battle in a neighbouring field, which, to this day, is 
called King’s-field, and their monuments are yet remain¬ 
ing in the church, which is a vicarage, with two chapels 
of eafe, value 500I. per aim. in the gift of the prebends of 
York. The carpet manufactory is carried on here in great 
perfection, being worked of any llze in one piece, with 
needles, by women ; and, in point of colours and ftrength, 
they are allowed to be the firft in the world. Broad and 
narrow cloths, cotton tapes, druggets, and gloves, are al- 
fo made here. 
AX'MOUTH, a village in the county of Devon, fitua- 
ted on the coaft, at the mouth of the river Ax, with a 
large bay : fix miles fouth-fouth-weft of Axminfter, and 
.153 weft of London. 
AX'UM, an ancient city, fuppofed to have been once 
the capital of Abyfiinia; the ruins of which are dill very 
extenfive. In one fquare, which feems to have been the 
centre of the town, there are forty obelifks. They are all 
of one piece of granite ; and, on the top of that which is 
entire, there is a patera, exceedingly weil executed, in the 
Greek ftyle. Axum is watered by a fmall dream, which 
flows all the year from a fountain contiguous to the row 
of obelilks. The fpring is received into a magnificent 
bafon of 150 feet fquare, and thence it is carried at plea- 
fure to water the neighbouring gardens, See. where, how¬ 
ever, there is little fruit except pomegranates; neither are 
thefe very excellent. 
AXUN'GIA,yi [from axis, Lat. an axle-tree, and znj- 
guo, to anoint.] Hog’s lard; greafe of any kind. 
Axungia Vitri, Sandiver, or Salt of Glass, a 
kind of fait which feparates from tlie glafs while it is in 
fufion. It is of an acrimonious and biting tafte. The 
farriers life it for cleanfing tire eyes of horfes. It is alfo 
made ufe of for cleanfing the teeth ; and it is fometimes 
applied to running ulcers, the herpes,, or the itch, by way 
of deficcative. 
AXY'RIS,y.' in botany, a genus of the clafs monoecia, 
order triandria, natural order holoracea;. The generic 
charaifters are—I. Male flowers in an ament. Calyx: pe- 
rianthium three-parted, fpreading, obtufe. Corolla: none. 
Stamina; filaments three, capillary, fpreading; anthers 
roundilh. II. Female flowers fcatteredi Calyx: perian- 
thiumfive-leaved (two-leaved, Syjl.) concave, obtufe, con¬ 
verging, permanent; the two outer leaflets (horter. Co¬ 
rolla: none. Piftillum: germ roundith ; (ivies two, ca¬ 
pillary; ftigmas acuminate. Pericarpiiun: none; calyx 
clofely involving the feed with its three larger leaflets. 
7 K Seed: 
