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On the Centie of the Circle B, moves the Index  which
is a circular Plate, having a Compafs in the Middle, whofe
Meridian Line anfwers to the Fiducial Line aa: at bb are
fix 'd two Pillars to fupport an Axis, which bears a YTelefce
like the former, whofe Line of Collimation anfwers to the
Fiducial Line aa.
At each End of either Telefc~te, is fix'd a plain Sight for
the viewing nearer Objeas. See SIGHT.
The Ends of the Index aa are cut circularly, to fit the
Divifions of the Limb B; and when that Limb is diago-
nally divided, the Fiducial Line at one End of the Index
Mews the Degrees and Minutes upon the Limb. The whole
Infirument is mounted with a Ball and Socket, upon a three-
leg'd Staff.
Moft 2Weodolites have no Telefcopes, but only four plain
Sights, two of them failen'd on the Limb, and two on the
Ends of the Index.
The Ufe of the heodolite is abundantly fhewn in that of the
Semicircle;whichisonlyhalfa Theodolite. See SEMICIRCLE.
And in that of theplain fable, which is occafionally made
to be us'd as a Theodolite. See PLAIN fable.
Note, the Index and Compafs of the Theodolite, like-
wife ferve for a Circumferentor, and are us'd as fuch. See
CIRCUMFERENTOR.
THEOGONY, that Branch of the Heathen Theology,
which taught the Genealogy of their Gods. See GOD.
Betod gives us the ancient Tlheogony, in a Poem under
that Title. Among the ancient Writers, Dr. Burnet ob-
ferves, 7Theogonv and Co6fmngony, fignify'd the fame Thing.
In efeEt, the Generation of the Gods of the ancient Per-
fians, Fire, Water, and Earth, is apparently no other than
that of the primary Elements. See COSMOGENY; fee alfo
CHAOS.
The Word is form'd from 'ts4, God, and pr' Geniture,
Seed, Off'pring.
THEOLOGY, call'd alfb     uivinity, a Science which
inilruas us in the Knowledge of God, and divine Things ; or
which has God, and the Things he has reveal'd, for its
Obje&. See GOD and DIVINITY.
Theology is a Doctrine which ihews us what we are to
think of God, and of the Manner wherein he would be
ferv'd. It is divided into two Branches, Natural, and Re-
veaj'd or Supernatural.
Natural Theology, is the Knowledge we have of God
from his Works, by the mere Light of Nature and Reafon.
See NATURE and REASON.
supernatural Theolcgy, is that which we learn from Reve-
lation. See REVELATION.
PofitiV6 THEOLOGY, is the Knowledge of the holy Scrip-
tures, and of the Signification thereof, agreeable to the Opi-
nions of the Fathers and Councils; without the Affiulance of
any Argumentation. Some will have it, that this ought to be
call'd expo/tive, notpofitive. See POSITIVE.
Moral THEOLOGY, is that which teaches us the divine
Laws relating to our Manners. See MORAL.
Schblaflic, or School THiEOLOGY, is that which proceeds by
Reafoning; or that derives the Knowledge of feveral divine
Things from fome eflabliflh'd Principles of Faith.  See
SCHOLASTIC.
The Ancients had a three-fold Theology; the firti pt'xery,
.Mythic, fabulous, which flourifh'd among the Poets; and
was chiefly employ'd in the Theogony, or Genealogy of
the Gods. See FABLE and FABULOUS; fee alfo THEO-
GONY.
The fecond, moArnxmV, Political, which was that chiefly
embrac'd by the Politicians, Prieas, and People, as mofd
fuitable and expedient to the Safety, Quiet, and Intereft of
the Stte.
The third, Puoa,"V, Natural, chiefly cultivated by the
Phi~ofophers, as nmott agreeable to Nature.
The Phyfical or Natural flheology acknowledg'd one only
fupreme God; to which it added Dxrmons, as Mediators
between him and Man. See DE MON.
The Word is compounded of aefa, God, and exes, Dif-
courfe
THEOLOGIUM, in the ancient Theater, was a Place,
or little Stage, above that whereon the ordinary Aators ap-
pear'd.
The flheologiun: was the Place where the Gods appear'd;
it alfo included the Machines whereon they defcended, and
from which they fpoke, See MACHINE.
There was a Theologium requir'd for the Reprefentation
of the Ajax of Sophocles, the Aiupoithus of Euripides, &c.
Scal. Poet. lib. 1. cap. x.
The Word is Latin, form'd from 3f, and Ao;of, Speech,
Di fcourfe.
THEOPASCHITES, a SefS of Hereticks, in the Vth
Century, the Followers of Petrs Fullenfis, or Peter the
Fuller.
Their difiinguifhing Doairine was, That the whole Ti-
* nity fuffer'd in the Paflion of jefjus CbriJi Sie PATRI-
FASSIA NS.


T H 1~',


This Herefy wis embrac'd by the Eurc        Monks ot
Scythia; who ufing their utmoft Efflorts to make it obtain,
: rais'd great Diforders toward the Beginning of the following
Century.
It was condemn'd at its firfm Rife, in the Councils of Rome
and Conf#aninople, held in 483 . It was reviv'd in the IXth
Century, and again condemn'd in a Council at Rome, held
in 86z under Pope Nicholas I.
IF. Rien, in his Notes on 5Damafcenus, fays, that the
fame Error had been taught before .Fullenjis, by Apollinarius,
whofe Difciples were the firft that were call'd Theopatites,
or h5eopafchites.
THEORBO, THEORBA, a Mufical InfIrument, made in
Form of a Lute ; except that it has two Necks, or Juga, the
fecond and longer whereof fuffains the four lall Rows of
Chords, which are to give the deepeft Sounds. See LUTE.
The Theorbo is an Infirument, which for thefe lafi fixty
or feventy Years, has Succeeded to the Lute, in the playing
of thorough Baffes: 'Tis faid to have been invented in
France by the Sieur Hotteman, and thence introduc'd into
Italy, &c.
The only Difference between the 9rbeorbo and the Lute,
is, that the former has eight Bafs or thick Strings, twice as
long as thofe of the Lute; which Excefs of Length renders
their Sound fo exceedingly lbftj and keeps it up fo long a
Time, that 'tis no Wonder many prefer it to the Harpfi-
chord itfelf. At leaft it has this Advantage, that it is eafily
remov'd from Place to Place, &c.
All its Strings are ufually fingle; tho' there are fome who
double the Bals Strings with a little Odave, and the imall
Strings with an Unifon; in which Cafe, bearing more Refem-
blance to the Lute than the common Theorbo, the Italians
call it the Archiluto or Aich-Lvte.
The Word Theorbo is form'd from the French Theorbej
of the Italian  liorba, which fignifies the lame Thing, and
which fome will have the Name of the Inventor.
THEOREM, in the Mathematical Method, a Propofition
which terminates in Theory, and which confiders the Pro-
perties of Things already made, or done. See THEORY
and PROPOSITION.
Or, ftrifdly, a Theorem is a Theoretical Propofition, de-
duc'd from feveral Definitions compar'd together. Thus, if
a Triangle be compar'd with a Parallelogram landing on the
fame Bafe, and of the fame Altitude ; and, partly, from
their immediate Definitions, and, partly, from other of
their Properties already determin'd, 'tis inferr'd, that the
Parallelogram is double the Triangle; that PropoAtion is a
Theorem. See DEFINITION, &c.
There are two Things to be chiefly regarded in every
Theorem, viz. the Propofition and the Demonflration: In
the firfi is exprefs'd what agrees to fome certain Thing under
certain Conditions, and what does not. See PROPOSITION.
In the latter, the Reafons are laid down, by which the
Underflanding comes to conceive that it does or does not
agree thereto. See DEMONSTRAT4ON.
Theorems are of various Kinds: Univerfal Theorem, is
that which extends to any Quantity without Refcridion, uni-
verlally 5 as this, That the Retfaxgle of the Sum and Diffe-
rence of any two kjeantities, is equal to the Dierence of their
Squares.
Particular Theorem, is that which extends only to a pay
ticular Quantity.
Negative, is that which expreffes the Impoflbility of
any Affertion ; as, That the Sum of two .Biquadirate Numbers
cannot make a Square.
Local Theorem, is that which relates to a Surface; as, 7That
T'riangles of the fame B'afe and Altitude are equal. See
LOCAL.
A plane TZheorem, is that which either relates to a Redi-
linear Surface, or to one terminated by the Circumference of
a Circle; as, That all Angles in the fame Semnt are equal
See PLANE.
A Solid Theorem, is that which confiders a Space termi-
nated by a folid Line; that is, by any of the three Conic
Sedions; e.gr. this, That if a right Line cut two Afymto-
tick Parabola's, its two Parts terminated by them #ball be
equal. See SOLID,
A Reciprocal Theorem, is one whofe Converfe is true; as;
That if a Triangle have rwo equal Sides, it mul have two
equal Angles: The Converfe of which is true, That if it
have two equal Angles, it mio have two equal Sides. See
RECIPROCAL.
THEORETIC, THEORETICAL, or THEoRcI, fome-
thing relating to Theory, or that terminates in Speculation ;
in which  Senfe the Word flands in Oppofition to Traffica.
'Tis form'd frbm the Greek, Aesofes, I fee, I contemplate
The Sciences are ordinarily divided into Theoretical, as
Theology, Philofophy, ec. and Praftical, as Medicine, Law,
0c. See SCIENCES.
In ancient Authors, Theoric Aioney was what was rais'd by
Way of Tax on the People, to defray the Expenes of The-
atrical Reprefentations, and other Spialaclcs.
Thero


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