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VERTEX, in Anatomy, the Crown of the Head 4 or
that Part fituate between the Sincciput and Occiput. See
HEAD.
Hence, alfo, Vertex is figuratively ufed for the Top of
other Things.
Thus, the Vertex of a Cone, Pyramid, Conic Seffion, 'jc.
is the Point of the upper Extremity of the Axis; or the
Top of the Figure. See CONE, PYRAMID, SC.
VERTEX of an Angle, is the angular Point; or the Point
A, (Tab. Geometry, Fig. I.) wherein the Legs meet. See
ANGLE.
VERTEX of a Figure, is the Vertex of the Angle oppofite
to the Bafe. See FIGURE.
Such is the Point M, (Tab. Geometry, Fig. 19.) oppofite
to the Bafe KL. See BASE.
VERTEX of a Curve, is the Point A, (Tab. Georm. Fig.-5.)
from which the Diameter is drawn; or the Interfedion of
the Diameter, and the Curve. See CURVE.
VERTEX of a Glafs, in Opticks, the fame with the Pole
thereof See POLE, OPTIC Glafis, &c.
VERTEX is alfo ufed in Afironomy, for that Point of Hea-
ven perpendicularly over our Heads. properly cali'd the Ze-
nith. See ZENrITH.
VERTICAL Circle, in Afironomy, is a great Circle of the
Sphere, pailing thro' the Zenith Z, and Nadir N, (Tab. A-
fironomy, Fig. 6.) and any other given Point in the Sur-
face of the Sphere. See CIRCLE, and SPHERE.
Thus, the Meridian of any Place is a Vertical Circle. See
MERIDIAN, LCe.
All the Vertic 11 Circles interfeea each other in the Ze-
nith and Nadir. See ZENITH, and NADIR.
The ufe of the Vertical Circles, is to meafure the Height
of the Stars, and their Diflances from the Zenith, which is
reckon'd on thefe Circles; and to find their Eaftern and
Weflern Amplitude, by obferving how many degrees the
Vertical wherein the Star rifes, or fets, is difiant from the
Meridian. See ALTITUDE, AMPLITUDE, SC.
The Vertical Circles are alfo called Azimuths. See Azi-
MUTH.
Prime VERTICAL, is that Vertical Circle, or Azimuth,
which pafes thro' the Poles of the Meridian ; or which is
perpendicular to the Meridian, and pafes thro' the Equinoc-
tial Points. See PRIME Vertical.
VERTICAL of the Sun, is the Vertical which paftes thro'
the Centre of the Sun, at any Moment of Time.
Its ufe is in Dialling, to find the Declination of the Plane
whereon the Dial is to be drawn; which is done by observing
how many Degrees that Vertical is difcant from the Meri-
dian, after marking the Point, or Line of the Shadow upon
the Plane, at any time. See DECLINATION.
VERTICAL Angles. Two Angles, as o and x, (Tab. Geo-
metry, Fig. i8.) are faid to be Vertical, if the Legs of one
of 'em, A E and E C, be only Continuations of the Legs of
the other, DE and BE. See ANGLE.
VERTICAL Plane, in Perfpeffive, is a Plane perpendi-
cular to the Geometrical Plane; palling thro' the Eye, and
cutting the Perfpecfive Plane at right Angles. See PLANE.
VERTICAL Plane, in Conicks, is a Plane palling thro' the
Vertex of the Cone, and parallel to any Conic Sedion. See
PLANE, and CONE.
VERTICAL Line, in Conicks, is a right Line drawn on
the Vertical Plane, and pafling thro' the Vertex of the Cone.
See LINE.
VERTICAL Dial, is a Sun-Dial, drawn on the Plane of a
Vertical Circle; or perpendicular to the Horizon. See DIAL,
and DIAL-Plane.
Thefe are particularly call'd Oriental, Eaft, Occidental,
Weft, Meridional, South, and Septentrional, or North Ver-
ticals, when oppofed to one, or other of thefe Cardinal
Points of the Horizon. See EAST, WEST, WtC.
When they don't look precifely to any of them, they are
call'd Decliners : And when their Plane, or Surface is not
perfedly perpendicular, Recliners. See DECLINER, RE-
CLINER, SeC.
VERTICAL Point, in Affronomy, the fame with VER-
TEX, or ZENITII.
Hence, a Star is faid to be Vertical, when it happens to
be in that Point which is jufi over any Place.
VERTICAL Line, in Dialling, is a Line on any Plane per-
pendicular to the Horizon.
This is bell found and drawn on an ere: and reclining
Plane, by holding up a String and heavy Plummetfleadily,
and then marking two Points of the Shadow of the Thread
on the Plane, a good diflance from one another; and draw-
ing a Line thro' thofe Marks. See DIALLING.
VERTICILLATE Plants, are fuch as have their Flow-
ers intermix'd with fmall Leaves, growing in a kind of
Whirls about the joints of a Stalk; as Penny-royal, Hore-
hound, Ac. See PLANT.
The peculiar Charac~eriflick of this Genus of Plants, at-
cording to Mr. Ray, is, that their Leaves grow by Pairs,
one jull againll another, on the Stalk: the Flower monope-


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talous, but utually hanging down with a kind of Lip, or
turned Something like the form of an Helmet: Four Seeds
after each Flower ; to which the Periantheum of the. Flower
fefves inflead of a Capfula Seminaiis.
The fame Author makes two Species of thefe Verticillate
Plants.
tO. The Fruticofie, or fuch whofe Superficies is Perennial:
Thefe, again, have either a plain Flower, as the Chamedrys
Vulgaris, 71hucrium, and the Marum Syrtacrim; or a
Flower with a Lip, which they call a Labiated Flower; or
one fomething in the form of an Helmet; which they call
Galeated; as the Sacria Stcechas, Hyffopus, Rofrnarinuso
Satureia, Marumm vulgare, T'hymum vulgare, and the Po-
lium Montanum.
f,A The Herbacee, or fuch whofe Stalks are not Peren-
nial; thefe are the Mentho, Verbena, Diaamnus Creticusi
Origanumi Majorana, Ocimumn, Horminum, Galeopfis, Ne-
peta, !Betonica, Prunella, Stachys, Clinopodium vulgare,
Lamium, Moluea Hedera 7errefiris, Galericularal Cala-
mintba, Meliffa, Marrubium Commune, nigrum and aquati-
cum; Chamepetys, Scarodonia, Scordium, Bugulai Syderi-
tis, Cardiaca.
VERTICITY, is that Property of the Loadflone, where-
by it turns to fome particular Point. See MAGNET.
The Attraffion of the Magnet was known long before its
Verticity. See COMPASS, NEEDLE, fe)C.
VERTIGO, in Medicine, an Indifpofition of the Brain,
wherein the Patient fees the Objeffs about him as if they
turn'd round, and fancies he turns round himfelf; tho all the
while at refd.
Phyficians diflinguilh two Kinds, or rather, two Degrees
of Vertigoes+ The firif, call'd a Simple Vertigo is when the
Body and external Objecds appear to turn roundf without any
great dimnefs of Sight.
The other, call'd Scotomia, or Vertigo 7enebrofai is when
the Eyes are darken'd, and as it were cover'd with a Mifl.
See SCOTOMIA.
Some make a third Stage, viz. a Vertigo Caduca, where-
in the Patient actually falls down: But this feems fcarce to
differ from an Epilepfy. See EItLEPsY.
Sometimes the Vertigo is feated in the fore-part of the
Head, and fometimes in the hind-part: whereof; the latter
is much the more dangerous.
Bellini accounts for the Vertigo very well, from a preter-
natural Motion in the Retina:, for 'tis evident, an Objeft
will feem to move circularly, if the Images thereof painted
on the Retina, fall fucceffively on diffirent Parts of We Re-
tina. See RETINA.
This they may do, either by the Objeas moving while
the Eye is at re , or from the Eye moving while the Objeffs
rell; or, lafily, the Object and Eye being both at reft, the
Rays falling on the fame Place by the Optic Nerve's be-
ing alone in Motion. For fince a right and an oblique Inci-
dence do not excite the fame Tremors in the Nerves, and
the fame Species of Motion ; if the Optic Nerve only be
moved, and the Objed be at rell, it will appear to fhitti its
Situation, by the Change of Place in which it was repre-
fented. See VISION.
External Caufes of Vertigines, are a continued turning
round of the Body, Drunkennefs, too long Faffing, immo-
derate Exercife, Surprize, Voracity, much ufe of P ulfe, O-
nions, Leeks, Raddilhes, Cabbage, Mullard, Fic. and in
the general, whatever may prefs, difiend, or contracl the
Arteries.
The Word is form'd 4 vertendo, from turning.
The firft Step in the Cure, is bleeding in the Jugular, or
Cupping; then they proceed to an Emetic; then a Vefica-
tory on the Neck, or a perpetual Blifler, or, ITues; with
Sternutatories, and the other Medicines that obtain in the
Apoplexy. See APOPLEXY.
VERTILLAGE, in Agriculture, the lilling, or prepa-
ring of Ground to receive the Seed, by turning, tirring, or
tolling it. See TILLING.
VERTUE. See VIRTUE.
VERTUOSO. See VIRTUOSO.
VERU-MONTANUM, in Anatomy, a Term compond-
ed of the two Latin Words, Vera, and Montanum; tignify-
ing a kind of little Valve, in the Place where the Ejacula-
tory Duds enter the Urethra. See VALVE, URETHRA, WC.
Its ufe is, to prevent the Urine, in palling the Urethra,
from getting in at thofe Duds, and fo mixing with the Se-
men. See!URINE, Wc.
VERY Lord, and VERY Tenant, are thofi; that are im-
mediate Lord and Tenant, to one another.
-And know ye, that in taokig of Leafes fix this
are neceffary, viz. Very Lord, and Very Tenant Service
behind ; the Day of the taking; Seira of the Services,
and within his Fee- and that a Man is Mt Very Tenant,
until he have atturned to the Lord bVy fin Serice.  Old
Nat. Brev.  See TsrA^NT, WC.
VEZS


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