AAX


( i83 )


A Z I


The Conjugate is the 1ihorter of the two Axe$ of ab Ellipis.
See CONJUGATE.
COnjagaie, Orfbred Axis of an IFtperbola, is the RIght Line
FF, Fig 32. drawn through the Centre parallel to the Ordinates,
M  N, M    N. perpendicularly to the Axis AP.  See HYPER-
BOLA.
The Length of this Axis, though more than infinite, may be
found by this Proportion, V/Awl x PM: AP     'MN: FF.
Axis of a Parabola. See PARABOLA.
The Axis of a Parabola is of an indeterijinate Length, that is
is infinite.-The Axis of the Elliplis is determinate.-The Para-
bola has only obe Axis; the Ellipfis and Hyperbola two.  See
CURVE.
Axis in Opticks.-Optk Axis, or Vifual Axis, is a Ray palling
through the Centre of the Eye; or it is that Ray which proceed-
ing out of the Middle of the luminous Cone, falls perpendicular-
ly on the cryftalline Humour, and confequently paffes through
the Centre of the Eye. See OPTIcK, RAYj CONE, VISION,
&c.
Common or mean Axis, is a Right Line drawn from the Point
of Concourfe of the two oprick Nerves, through the Middle of
the right Line, which joins the Extremity of the fame optick
Nerves. See OPTICK Nerve. .
Axis of a Lens, or Glafi, is a right Line palling along the Axis
of that Solid whereof the Lens is a Segment. See LENS and
GLASS.
Thus a Spherical convex Lens, being a Segment of
fome Sphere; the Axis of the Lens is the fame with the Axis of
the- Sphere; or it is a right Liue pailing through the Centre there-
pf. See CONVEX, &c.
Or the Axis of a Glafs is a right Line joining the Middle Points
of the two oppofire Surfaces of the Giaf. See OPTICK Wlafs.
Axis of Incidence, in Dioptricks, is a right Line drawn through
the Point of Incidence, perpendicularly to the refraating Surface.
See INCIDENCE.
Such is the Line DB, Tab. Opticks, Fig. 56.
Axis of Refraffion, is a right Line continued from the Point
of Incidence or Refraftion, perpendicularly to the refraating Sur-
face, along the further Medium.-Such is the Line BE.
Or it is that made by the incident Ray, perpendicularly pro-
longed on the Side of the fecond Medium. See REFRACTION.
.AXIS of a agnet, or Magnetical Axis, is a Line paffing thro'
the middle of a Magnet, length-wife; in fuch manner, as that
however the Magnet be divided, provided the Divifion be ac-
cording to a Plane wherein fuch Line is found, the Loadftone
will be made into two Loadftones.  See MAGNET and MAG-
NETISM.
The extreams of fuch Lines are called the Poles of the Stone.
See POLE and POLARITY.


Axis, in Anatomy, is the third Vertebra ot the NeCK; recx-
oning from the Skull. See VERTEBRA.
"1 is thus called by reafon the two firft Vertebroe, with the
Head, move thereon, as on an Axis. See HEAD and NECK.
Spiral Axis, in Architeature, is the Axis of a twilted Co-
lumn, drawn fpirally, in order to trace the Circumrvolutions with-
out. See Tsaifled C:OLU.MN.
AXIS of the lonick Capitol, is a Line pagfing perpendicularly
through the middle of the Eye of the Volute. See IONIC and
VOLUTE.
The Axis is otherwise call'd Catbetaus. See CATHETUS.
Axis in Peritrochio, is one of the five mechanical Powers, or
fimple Machines; contrived chiefly for the railing of Weights to
a considerable Height. See MECHANICAL Power, &C.
It confifts of a Circle, represented AB, (Tab. Mechanicks, Fig.
4.) concentric with the Bafe of a Cylinder, and moveable to-
gether with it, about its Axis EF.-This Cylinder is calPd the
axis; the Circle, the Peritrochium; and the Radii, or Spokes,
which are fometimes fitted immediately into the Cylinder, with-
out any Circle, the Scytalke. See PERITROCHIUM.
Round the Axis winds a Rope, whereby the Weight, &c. is
to be rais'd.
The Axis in Peritrochia takes place in the Motion of every
Machine, where a Circle may be conceived described about a
fix'd Ai concentric to the Plane of a Cylinder about which
it is placed; as in Crane-Wheels, Mill-Wheels, Capftans, &c.
See WHEEL.
Doarine of the AX  in Peritrochio.
i. If the Power, applied to an Axis m Peritrochia, in the Di-
re~tionAL,Fq.7. perpendicular to 'the Periphery ofthe Wheel, or to
the Spokes be to a Weight G, as t adius of the Axis CE, is
to the Radius of the Wheel CA, o the Length of the Spoke;
the Power will juft fuftain the Weight, i. e. the Weight and the
Power will be ix Ejuilibrio.
i. If a Power be applied to the Wheel in F, according to the
Line of Dire&ion FD, which is oblique to the Radius of the
Wheel, thou   parallel to the perpendicular Dire&ion; it will
have the fame Prportion to a Power which as according to
the perpendicular Direaion AL, which the whole Sine has tK
the Sine of the Angle o the Direcaion DFC.


Hence, fince the Diftance of the Power in A, is the Radlu8
CA; the Angle of Direaion DFC being given; the Diftance DC
is eafily found.
3. Powera applied'to the Wheel in fevefal Points, F and K,
according to the Dire&ions, FD and KI, parallel to the perpen-
dicular one AL, are to each other as the Diftances from the
Centre of Motion CD and DI, reciprocally.
Hence, as the Diftance from the Centre of Motion incieafes;
the Power decreafes;  - wce verfit-Hence alfo, fince the Ra-
dius AC is the greateft Dittance, and agrees to the Power a6t-;
ing according to the Line of Diredtion; the perpendicular Power
will be the finallefl of all thofe able to fuftain the Weight G.
according to the feveral Lines of Diredtion.
4. If a Power aaing according to the Perpendicular AL, lift
the Weight G; the Space of the Power will be to the Space
of the Weight, as the Weight to the Power.
For, in each revolution of the Wheel, the Power paffes tbro'
its whole Periphery; and in the fame time the Weight is rais'd i
Space equal to the Periphery of the Axis: The Spice of the
Power, therefore, is to the Space of the Weight, as the Peri-
phery of the Wheel to that of the Axis: But the Power is to the
Weights as the Radius of the Axis to that of the Wheel. There-
fore, &c.
5. 4 Po'rer, and a Weight being given, to tonJrut ax Axis in
Peritrochio, whereby itJball be Jkfaix'd.
Let the Radius of the Axis be big enough to fupport the
Weight without breaking. Then, as the Power is to the Weight;
fo make the Radius of the Wheel, or the Length of the Spooe,
to the Radius of the Axis.
Hence, if the Power be but a fmall part of the Weight, the
Radius of the Wheel mull be vaftly great.-E. gr. Suppofe the
Weight 3000, and the Power 5o, the Radius or the Wheel will
be to that of the Axis as 6o to I.
This Inconvenience is provided againft by encreafing the num-
ber of Whxels and Axes i and making one turn round anotheri
by means of Teeth or Pinios. See WHEEL.
AXUNGIA, a kind of Far, the fo teft and moiffeft of any
in the Bodies of Animals. See FAT.
It is different from Lard, which is a firm Fat; and from Suet
Leaf, or Adeps, which is a kind of dry Fat.
The Latins diftinguifl Fat into PingAuedo, call'd alfo Zxungia;
and Adleps, or Sevum; buc many of our modern Writers confound
them. SeePINGUEDO.
The Phyficians make ufe of the dxungia of the Goofe, the
Dog, the Viper, and fome others, efpecially that of Man, which
is of extraordinary Service in the drawing and ripening of Tu.
mors, &c. See ATTRAHENT. See alfo VIPER, &C.
The Word is fuppofed to be forn'd, ab Xxe Retarum qiu uat-
guntur.
AXUNGIA of Gla/i, call'd alfo the Gall, and Salt of Glafs) is a
Scum taken from the Top of the Matter of Glafs before it be
vitrified. See GLASS.
AYEL, in Law, a Writ wh'ch lies where the Grandfather be-
ing feized in his Demefn the Day he died, a Stranger enters the
fame Day, and difpoffeffes the Heir. See WRIT.
AYRY, or Aery of Hawks, a Nell or Company of Hawks;
fo call'd from the old French Word Aire, which fignifies the fame
thing. See HAWK and HAWKING
AYZAMENTA. See EASE \!ENTS-
AZIMUTH, in Aftronomy.-The Azimuth of the Smn, or a
Star, is an Arch of the Horizon, comprehended between the
Meridian of the Place, and any given Vertical. See MERIDIAN
and VERTICAL.
The Azimuth is the Complement of the Eaftern and Weftern
Amplitude to a Quadrant. See AMPLITUDE.
The Azimuth is found by this Proportion; as Radius is to the
Tangent of the Latitude, tb is the Tangent of the Sun's Altitude
to the Cofine of the Azimuth from the South, at the time of the
Equinox.
To find the Azimuth by the Globe, fee GLOBE.
The Word is pure Arabick, where it fignifies the fame thing:.
.MagneticatAzl~U'rH, is an Arch of the Horizon contained
between the Sun's Azimuth-Circle, and the magnetical Meridian;
or it is the apparent Diftance of the Sun from the North or South
Point of the Compafs. See MAGNETICAL.
It is found, by observing the Sun with an Azimuth Compafs,
when he is about Io or 15 Degrees high, either in the Forenoon
Afternoon. See Azimutb COMPASS.
AZIMUTH Compafi is an Iriftrument ufied at Sea for finding the
Sun's magnetical Azimuth. ' See Magnetical AZIMUTH.
The Defaiption and Ufe of the Azimuth compafi, fee under
the Article Azimuth COMPASS.
AZIMUTH Dial, is a Dial whofe Style or Gnomon is at right
Angles to the Plane of the Horiton. See DIAL.
AZIMUTHS, call'd alfo vertical Circles, are great Circles inter-
feaing each other in the Zenith and Nadir, and cutting the Ho-!
rizon at right Angles. See VERTICAL,
The Horizon being divided into 36o'; for this reafom they
uffually conceive 360 Aim*ths.-Thefe Azimuths are repreent-
ed by the Rhumbs fin Sea Charts.  See HORJzON} RHtMU,
CHART,e &f.
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