Page:Cyclopaedia, Chambers - Volume 1.djvu/376

 C I R

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C I R

All the Stars included within this Circle never fet, but are ever vifible above the Horizon.

The Circle of perpetual OcculUtida, is another Circle at a like Diftancc from the Equator; and contains all thofe Stars which never appear in our Hemifphere. See Occul-

TATION. , T

The Stars fituate between thefe Circles, alternately rile and fet at certain Times. See Star, Rising, Setting, &c

Circles of -Pojltion, are Circles pafling thro the com- mon Interferons of the Horizon and Meridian, and thro any Depree of the Ecliptic, or the Centre of any Star, or other Point in the Heavens ; us'd for finding out the Situa- tion or Pofition of any Star, t$c. See Position.

They are ufiially made fix in number ; and cut the Equa- tor into twelve equal Parts, which the Aftrologers call the Celefiial Monfes. . „,„.,,. -

Hence fome call them Circles of the Celeftial Bmfes.

Circle, in Phyficks, is underftood, among the School- men, of a Viciffitude of Generations, arifing one out of another.

Thus, good Concoction caufes a good Habit of Body ; a good Habit of Body produces Strength and Vigour ; thefe occafion frequent Exercifes ; and thefe a good Concoftion.

'Tis a celebrated Dogma of the Scotiffs, ' There is no ' Circle in Caufes of the fame Order, or Kind.'

Circle, in Logick, the Fault of an Argument that fup- pofes the Principle it mould prove, and afterwards proves the Principle by the Thing it feom'd to have prov'd.

Or, a Circle in Logick, call'd alfo Syllogiftic Circle, is when the fame Terms are proved, in Orbem, by the lame Terms ; and the Parts of the Syllogifm, alternately by each other, both directly and indirectly.

There are two Kinds of Circles ; the one Material, the other Formal.

The Formal is that which in two reciprocal Syllogilms begs the Medium, which is the next Caufe of the greater Extreme. This Kind is by no means to be admitted : otherwife, the fa me Thing becomes both prior and pofterior; the Caufe and Effect of it felf ; which is abfurd.

The Material Circle, call'd alfo Regreffus, confifts of two Syllo.-ifms, the former whereof proves the Caufe by the Ef- fea ; and the latter the Effea by the Caufe : This may be admitted.

Circles of the Empire, are fuch Provinces, and Princi- palities of the Empire, as have a Right to be prefent at Diets. See Empire, and Diet.

The Divifion of the Empire into fix Circles, was efta- blifh'd by Maximilian I. in 1500, at Ausburg : twelve Years afterwards he divided it afrefh, into ten Circles; which Partition was confirm'd by Charles V. at the Diet of Nurem- berg, in 1522.

Tho the Order of thefe Circles has never been well regu- lated ; yet, in the Imperial Matricula, it is as follows: The Circle of Auftria, that of Burgundy, of the Lower Rhine, of "Bavaria, Upper Saxony, Franconia, Suabia, Upper Rhine, IVeftphalia, and the Lower Saxony.

CIRCUIT, or CIRCUITY, in Law ; a longer Courfe of Proceeding to recover the Thing fued for, than is needful.

Thus, if a Man grant a Rent-Charge of 10/. out of his Manor, and after, the Grantee diffeizeth the Grantor of the fame Manor, who brings an Affife, and recovers the Land, and 20/. Damages: which being paid, the Grantee brings his Aftionfor 10/. of his Rent, due during the Time of rheDiffei- fin, and which he muft have had if no Diffcifin had been : This is call'd Circuit of Action ; becaufe, whereas the Grantor was to receive 20/. Damages, and to pay 10/. Rent, he mii>ht have recciv'd but 10 /. for Damages, and the Grantee have kept the other.

Circuit, is alfo the Journey, or Progrefs the Judges take, twice every Year, thro' the feveral Counties of England and Wales, to hold Courts, and adminifter Juftice, where re- courfe cannot fo well be had to the King's Courts at Weft- minjler. See Judge, and Assize.

CIRCULAR, any thing that is defcrib'd, or mov'd in a round 3 as the Circumference of a Circle, or the Surface of a Globe. See Circle.

The circular Form is of all others the beft difpos'd for Morion ; and the moil capacious.

The modern Affronomers fhew, that the Heavenly Bo- dies don't move in Circular, but in Elliptic Orbits. Sec Or- bit, Planet, igc.

Circular Lines, in Mathematicks, are fuch ffrait Lines as are divided from the Divifions made in the Arch of a Circle.

Such are Sines, Tangents, Secants, £5?c See Sine, Tan- gent, Z$c. .

Circular Velocity, a Term in Attronomy, fignifying that Velocity of a Planet, or revolving Body, which is meafur'd by the Arch of a Circle : as fuppofe by A b, (Tab. Aftron. Fig. 10.) defcrib'd on the Centre of AttraQion S.

The circular Velocity of a Body moving from B to C, is meafur'd by the Ark B C.

Circular Numbers, are fuch whofe Powers end in the

Roots themfelves ; as 5, whofe Square is 25, and Cube 1;;. See Number.

Circular Letter, a Letter dircfled to feveral Perfons, who have the fame Intereft in the fime Affair 3 as in the Convocation of Affemblies, STe.

Circular Sailing, is that perform'd in the Arch of a great Circle. Sec Sailing.

Circular Sailing, of all others, goes the neareftor fhorteft way : and yet there are fuch Advantages in failing by Rhumbs, that this latter is generally preferr'd.

CIRCULATION, the Afl of circulating, or moving i n a Circle. See Circle.

Thus, we lav, The Circulation of the Blood ; the Circu- lation of the Sap ; of the Spirits, &c. See Blood, Sap, ■ Spirits.

As in the great World we find a perpetual and orderly Cir- culation of Waters, convey'd from the Sea by fubterraneous ' Paffagcs, Springs, SSc. and rctum'd thither again by Rivers, (gc. ib in the little World, Man, a like Circuit is obferv'd ; the Blood being continually driven from the Heart, by the Arteries, to all Parts of the Body ; and brought back again to the Heart by the Veins. See Heart, Vein, and Arterv.

Circulation of the Stood, a natural Motion of the Blood in a living Animal ; whereby that Humor is alternately con- vey'd from the Heart to all the Parts of the Body, by the Arteries, and return'd from the fame Parts to the Heart by the Veins. See Blood.

The Heart, we have elfewhere fhewn, is a Mufcle, into the Ventricles or Cavities whereof, all the Veins difcharge themfelves, and from which all the Arteries arife ; having, withal, a reciprocal Action of Dilatation, or Dtaftole ; and Conftriclion, or Syftole. See Heart, Svstole, and Dia- stole. • . a. . ,

Now, the neccflary Effea of fuch alternate Action, is, that the Heart, by turns, both receives and expels the Blood. The Blood expell'd out of the right Ventricle, mull be car- ry 'd thro' the 'Pulmonary Artery (which arifes thence) into the Lungs ; from which it muft be return'd, by the Pulmo- nary Vein, to the left Ventricle, (in which that Vein termi- nates.) From the left Ventricle, the Blood thus imported, is by the Conflriftion of that Part, again expell'd into the Aorta, and by it distributed all over the reft of the Body ; and thence return'd again to the right Ventricle by the Cava, which compleats the Circulation. See Pulmonary Artery, and Vein; Cava, and Aorta.

The Circulation of the Blood, has been generally allow d to have been firft difcover'd in England, in the Year 1S28, by Harvey, a Phyfician of our own Country ; tho there are feveral Authors who difpute it with him.

fanfen de Almeloveen, in a Treadfe of New Inventions, printed in 10-84, quotes feveral Paflages from Hippocrates, to prove that the Circulation was known to him.

WaUus, (Ep. ad Sartbol.) and Carleton, (Oecon. Amm.) pretend, 'twas known not only to Hippocrates, but alfo to 'Plato and Ariflotle.

'Tis added, that the Chincfc Phyficians taught it 420 Years, e're it was fpoke of in Europe.

Some go back as far as Solomon, and imagine they fee fome Traces of it in Ecclefiafles, Chap. xii.

Bern. Genga, in an Italian Treatife of Anatomy, quotes feveral Paffages from Realdus Columbus, and And. Cefil- finus, whereby he endeavours to prove that they admitted a Circulation, long enough before Harvey.

He adds, thar Fra. Paolo Sarpio the famous Venetian, from a Consideration of the Smifture of the Valves of the Veins, and other Experiments, concluded a Circulation. See Valvi.

Leonicenlis adds, that F. adua ; and who, upon his return to England, a Country of Liberty, publifh'd it as his own.

The Circulation of the Blood is evine'd, from the fol- lowing Confiderations.

1. All the Blood of a living Animal, upon wounding any one of the larger Arteries, is, in a little time, evacuated ; and that with a confiderable force: as appears from the Ope- rations of Butchers, £S?c.

Hence, it follows, that the Blood has a Paffiige from every Part of the Animal Body into every Artery : and if tM whole Mafs of Blood be found to move on this occafion, tis evident it muft have mov'd before.

1 The great Quantity of Blood driven out of the Hear' into the Arteries at every Pulfe, makes a Circulation need- fa ry 5 fince, without it, an infinitely greater Stock "J J? 100 muft be fuppos'd in the Body of a Man, than any Oblerva- tion or Experiment will allow -of.

For tho the Anticnts, who knew not this Circulation, ,™»t gin'd that only a Drop or two was expell'd at each f>yitai , which they were neceffuated to fuppofe, to avoid the i too