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But after him came Aftronomers, who, With .ft little
tnorePhyfics, have made no difficulty of changing thefe cir- cular Orbits into Elliptic ones ; and of making 'em move with different Velocities in different Parts thereof.
Of thefe Elliptic Orbits, there have been two kinds al- lien 'd : The firft, that of Kepler, which is the common Ellip- fi° ; to which Setb Ward, tho" he himfelf keeps to it, thinks one might venture to fubftitute circular Orbits, by ufingtwo Points taken at equal Diftances from the Centre on one ot their Diameters, as they do in the Foci of the Ellipiis. The fecond is that of M. Caff.ni ; whofe CharaSer is this, that the Prod U a S of the right Lines drawn from each Point of its Circumference are every where equal ; whereas in the common Ellipfis, 'tis the Sum of thole right Lines that is always the fame. See Ellipsis. ^ ,
M. Varignon fhewshow inconfftient Copernicus s Sentiment is with the Mechanifm of the Heavens : Since the Forces which Planets have to retain 'em in their Orbits, muft al- moft always confpire to make 'em move with really dif- ferent Velocities 5 and that among an infinity of Cafes, there is but one wherein they can move uniformly.
The Semi-diameter of the Earth's Orbit, Dr. Gregory makes 94,696 ,oiSo Miles Englifi ; and the Semi-diameteroi Saturn's Orbit about 10 times as great.
The Orbits of the Planets are not all in the iame Flane as the Ecliptic, or the Earth's Orbit round the Sun ; but variouily inclined to it, and to one another. But ftill the Plane of the Ecliptic interfeas the Plane of the Orbit of every Planet in a right Line, which paffes through the Sun. See Inclination. ; ..
The Quantities of the Inclinations of the Planes ot the Orbits of the primary Planets to that of the Ecliptic, are as follow : That of Saturn, is an Angle of 2 Degrees x : That of Jupiter, an Angle of 1 Deg. ao Mm. That ot Mars is almoft 1 Deg. Peons is a little more than 3 Deg. ao Min. And that of Mercury a little more than 7 Degr. See Saturn, Mars, Venus, &c.
The Orbits of Comets, Cafni takes to be Reflilmear ; but Dr. Halley, from Sir Ifaac Nekton's Theory, (hews them to be parabolical, having the Sun in one of their Foci. See Comet. . . ,
Orbits, in Anatomy, the two large Cavities, wherein the Eyes are plac'd. See Eye. •
Their Figure is pyramidal : They are form d ot talc- veral Bones ; and are perforated at bottom, to give paffage to the Optic Nerves.
ORBITER, in Anatomy, a Name fometimes given to two Holes or Cavities, either from their Refemblance of, or Nearnefs to, the Orbits of the Eyes.
The Orbiter Externa:, is the Hole in the Cheek-Bone be-
l °Vuo%el'ltiter,,us, is a Hole in the Coronal-Bone of of the Scull, within the Orbit. See Coronal.
ORCHARD, a Seminary or Plantation of Fruit- 1 tees, chieflv Apples. See FRuiT-Tree.
'Tis a Rule among Gardeners, that thole Orchard: Mn paribus, thrive beft, which lie open to the South, South-Weft and South-Eaft; and are fcreen'd from the North : the Soil
Ar oX^are flock'd byTranfplantation; feldom by Se- mination. See Planting, Nursery, ($c
The Seafon for tranfplanting Apple-Trees into Orchards, is in the Months OBober and November. If the Leaves be not •ill off at the time they are remov'd, they muft be pull d off They are likewife to be prun'd. Trees may be trans- planted into Orchards after three Years Grafting ; and ought not to be fet at alefs diftance than eight Yards, nor greater than fourteen : And the richer the Land, the greater the
Diftance. _ r ,
The Trees are tranfplaoted to beft purpofe, when young; for Trees ten or twelve Years old, a narrow Trench muft be dug the November before, deep enough to meet the Wading Roots, at fuch a diftance all around the Tree, as the Roots are to be cut off at. In making the Trench, the Roots to be cut off clean, and without fplitting or bruiting the Bark, and the Trench fill'd up again. This will ena- ble the Tree, upon Removal, to draw more Nourifhment than otherwife it would, and fo thrive better in its new Manfion. See Transplantation, Inoculation, En- grafting, £5c.
The Side-Branches of all tall Orcbard Bruit-frees, arero be cut off till the Tree be arriv'd at the height defir'd. If the Tree be to fpread low, fome are to be left on each Side- fo as to form a kind of Balance. For the firft three' Years, at leaft, they muft not grow thick and bufhy- headed ; this muft be prevented, by cutting off fome of the inlide Shoots, and fuch as grow crofs each other, or pendant. See Pruning. .
The Soil if not rich enough, is to be amended in two or three Years ; by opening it around the Tree, and on the eutfide the Ground firft dug, when the Tree was fet; and
in a Month's time filling it up again with a proper Cotnp (i or Manure. See Manure; fee alio Pruning and Com- post.
ORCHESTRA, in the Drama, the lower part of the antient Theatre ; made in form of a Semi-Circle, and furrounded by the Seats. See Theatre.
It was fo call'd, becaufe in the Grecian Theatres it was a Place where they kept their Balls ; from og>, s7,3a/, which fignifies to dance.
The Orcbefira among the Greeks made a part of the Scene; but on the Roman Theatres, none of the Actors went down to the Orchejira, which was taken up with Seats for the Senators ; anfwering nearly to the Pit in our Theatre. See Scene, tiff.
ORDEAL, or Ordael, or Ordel Purgation, a Form of Tryal, i. e.. of evincing Innocence or Guilt; practis'd in England in the time of Edward the Confeffbr, and fince, as low as King John and King Henry III. See Tryal.
It was call'd Pttrgatio Vulgaris, or Judicium, in oppofition to Bellum, or Combat, the other Form of Purgation. See Purgation and Combat.
The Practice of Ordeals did not only obtain in England, but alfo in France and Germany : It was condemn'd by Pope Stephen II. and abolilh'd by a Declaration of Henry
The Ordeal was of various Kinds, viz. that of Fire, that of red hot Iron, that of cold Water, that of judicial Pot- tage, that of hillow'd Cheefe, that of boiling Water, that of the green Crofs, and that of Dice laid on Relicks, cover'd with a woollen Cloth. -v.
But the more popular Kinds were thofe or red-hot Iron and Water : the firft for Freemen, and People of fafhion ; thefecond&r Peafants. See Judicium, Fire, Wahr^i.
'Tis a popular Story in our Hiftones, that Emma, Mother of Edward the ConfeJJor, being accus'cl of too much Familia- rity with the Biihop ef Leicejier, uemanoed the Ordeal of red-hot Iron ; and pafs'd bare- tooted, and hood- wink'd, over nine red-hot Plougn-fhares, without touching any ot them.
The Word, in the original Saxon, fignifies a great Judg- merit. There were particular Maffes tor thefe Ordeals.
ORDEFF, or Oredeef, a Word frequently ufed in Charters of Privileges, for a Liberty whereby a Man claims the Ore found in his own Gruund. See Ore.
It properly fignifies Ore lying under ground ; as, a Delf of Coal, is Coal lying in Veins under ground.
ORDER, in Architecture, a Syttem of the feveral Members, Ornaments, and Proportions of Columns, and Pilaiiers : Or, a regular Arrangement of the projefting Parts of a Building; efpecially thofe of a Column: fo as' to form one beautiful Whole. See Column.
Perrault defines an Order to be what is regulated by the Ordonnance, when it prefcribes the Proportions of entire Columns, and determines the Figure of certain Parts proper to them, according to the different Characters their different Ufes and Ends require. See Ordonnance.
M. leClerc defines an Order to be a Cjlumn charg'd with an Entablature, and fupported on a Pedettal.
The Definitions Vitruvius, Barbara, Scamozzi, iSc. give of Order, are fo obfeure, that it were vain to repeat them : without dwelling, therefore, on the Definition of a Word, which Cuftom has eftablifh'd ; 'tis fufficient to obferve, that there are five Orders of Columns; three whereof ire Greek, viz. the Doric, Ionic, and Corinthian ; and two Italic, viz. the Tufcan, and Composite.
The three Greek Orders reprefent the three different Man- ners of Building, viz. the Solid, Delicate, and Mean ; the two Italic ones are imperfect Productions thereof. The lit- tle regard the Romans had for thefe laft, appears hence, that we don't meet with one Inftance in the Antique, where they are intermix'd. That Abufe the Moderns have intro- due'd, by the Mixture of the Greek and Latin Orders, Da- viler obferves, arifes from their want of Refleflion on the Ufe made thereof by the Antients.
The Origin of Orders is almoft as antient as human So- ciety : The Rigour of the Seafons firft led Men to make little Cabins, to retire intos at firft, half under ground, and the half above, cover'd with Stubble : At length growing more expert, they planted Trunks of Trees an-end, laying others a-crofs, to fuftain the Covering. See Architec- ture.
Hence they took the Hint of a more regular Architec- ture ; for the Trunks of Trees, upright, reprefent Columns: the Girts, or Bands, which ferv'd to keep the Trunks from burfting, exprefs'd Bafes and Capitals ; and the Sum- mers laid a-crofs, gave the Hint of Entablatures; as the Covetings, ending in Points, did of Pediments. Tnis is Vitruvius's Hypothetis ; which we find very well illuftrated by M. Bhniel. See Capital, Pedestal,£?<:.
Others take it, that Columns took their Rife from Pyra- mids, which the Antients erected over their Tombs ; and that the Urns, wherein they enclos'd their Allies, repre-
fented
