Page:Cyclopaedia, Chambers - Volume 2.djvu/649

 ROT

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ROT

The Rofirum was a Kind of Chapel, taken out of the Forum, and fumiihed with a Suggefturo, or Eminence, call'd alfo the Roftra, where the Orators fpoke.

It was adorn'd, or, as Livy fays, built, with the Beaks of Ships taken from the People or" Antium, in a Naval Engagement; whence theName. See Rostrum.

ROSTRALIS Corona, Rostral Crown, in Antiquity. See Crown.

Rostralis Columna, Rostral Column. See Column.

ROSTRI-Formis Procetfus, in Anatomy, the fame as Coracoides. See Coracoides.

ROSTRUM, inChymiftry, figniiies the Nofe or Beak which conveys the Liquor diftiil'd, into its Receiver ; in the common Alembicks. See Alembick, Receiver, Distillation, &c.

Rostrum, is alfo a crooked Scilfars, which the Surgeons in fome Cafes make ufe of for the Dilatation of Wounds.

Rostrum litterally denotes the Beak or Bill of a Bird. See Bill.

Hence the Word is alfo figuratively underftood of the Beak, or Fore-part of the Head of a Ship. See Head, Ship, &c. See alfo Rostra.

ROSYCRUdANS, Rosicrucians, or, Brothers of the ^Ro- sy-Cross, a Name affumed by a Sect or Cabal of hermetical Philofophcrs ; who arofe, or at leaft became firft taken Notice of in Germany* in the Beginning of the laft Century. See Her- metical.

They bound themfelves together by a folemn Secret, which they fwore inviolably to preferve; and obliged themfelves at their admiffion into the Order, to a ftrict Obfervance of certain efta- blifh'd Rules.

They pretended to know all Sciences, and chiefly Medicine ; whereof they published themfelves the Reflorers. —They pretend- ed to be Matters of abundance of importantSecrets; and among others, that of the Philofbphefs Stone ; all which they affirnfd to have received by Tradition from the antient Egyptians, Chal- deans, the Magi) and Gymnofophifts. See Philosopher^-S^w.

Their Chief was a German Gentleman, educated in a Mona-

ftery, where he learnt the Languages In 1578 he went to the

Holy-Land, where falling Sick at Damafcus, he : confuked the Arabs, and other Eafiem Philofophers, by whom he was fuppo- fed to be initiated into this wonderful Art. — At his return into Germany, he form'd a Society, to whom he communicated the Secrets he had brought with him out of the Eafi, and died in 1484..

They have been diftinguifhed by feveral Names, accommo- dated to the feveral Branches of their Doctrine — Becaufe they pretended to protract the Period of human Life, by means of certain Nsflrums, and even to rcflore Youth ; they were calfd Immortalss.

As they pretended to know all things, they have been call'd fflummatij and becaufe they have made no appearance for feve- ral Years, but have kept altogether incog, they have been call'd the Iwviftbk Brothers.

Their Society is frequently fignified by the Letters F. R. C. which fome among them interpret Fratres roris cocli, it being pretended that the Matter of the Philofopher's Stone is Dew con- cocted, exalted, &c.

Some, who are no Friends toFree-Mafonry, make the prefent flourifhing Society of Free-Mafons a Branch of Rof crucians ; or rather the Roficrucians themfelves under a new Name, or Relati- on ; viz. as Retainers to Building. — And 'tis certain, there are fome Free-Mafons who have all the Characters of Rofcrucians ; but how the ^Era and Original of Mafonry, as traced by Mr. Anderfin, and that of Rofcrucianifm, here fix'd from Naud&xs, who has wrote exprelly on the Subject, confift, we leave oihers to judge. See Masonry.

ROT, a Difeafe, which in moift Years is incident to Sheep, in the fame Ground, where in drier Years they are free from it ; which, yet, arifes, not only from the Moifture, but from a cer- tain Principle of Putrefaction, both in the Air and the Grafs. See Rottenness.

ROTA, in Mechanicks. See Wheel.

Rota Arifiotelica, Arijfotle's Wheel) is a celebrated Problem in Mechanicks, founded on the Motion of a Wheel about its Axis; thus called, becaufe firft, that we know of, taken Notice of by Arifiotk.

The Difficulty is this. — While a Circle makes a Revolution on its Centre, advancing at the fame time in a Right Line along a Plane; it defcribes, on that Plane, a Right Line equal to its Cir- cumference. Now if this Circle, which we may call the defe- rent, carry with it another fmaller Circle concentric with it, and which has no Motion but what it receives from the deferent; which is the Cafe of the Nave of a Coach-Wheel carried along by the Wheel ; this little Circle, or Nave, will defcribe a Line in the time of the Revolution, equal, not to its own Circumfe- rence, but to that of the Wheel : For that its Centre advances in a Right Line, as faft as that of the Wheel does ; as being in re- ality the fame therewith.

The Matter of Fad is certain.— But how it fhould be feems a Myftery.— "Tis obvious, that the Wheel advancing during the Revolution, tnuft defcribe a Right Line equal to its Circumfe T

rence; but how mould the Nave, which revolves like the Wheel, defcribe a Right Line fo much greater than its Circumference ?

The Solution Ariftotle gives is no more than a good Explica- tion or the Difficulty.

Galileo, who attempted it, has recourfe to an Infinity of infi- nitely little Vacuities in the Right Line defcribed by the two Circles; and imagines that the little Circle never applies its Cir- cumference tothefe Vacuities; but in reality only applies it to a Line equal to its own Circumference; though it appears to have applied it to a much larger.

But 'tis evident this is all gratis diclum.— -The Vacuiries are ima- ginary; and why does not the great Circle apply its Circumfe- rence to them? Laftly, the Magnitude of thefe Vacuities mull be augmented or diminifned according to the different Propor- tion of the two Circles.

F. Tacquet will have it that the little Circle making its Rotati- on more llowly than the great one, does on that Account de- fcribe a Line longer than its Circumference; yet without ap- plying any Point of its Circumference to more than one Point of its Bafe. — But this is no more allowable than the former.

The Attempts of fomany great Men proving vain; M. if Or- tous de Meyram, a French Gentleman, had the good Fortune to hit on a Solution, which he fent to the Royal Academy of Sciences; where being examined by Men" fa Lowville and Saul- mon, appointed for that purpofe, they made their Report that k was Satisfactory.— The Solution is to this effect.

The Wheel of a Coach is only acted on, or drawn in a Right Line : Irs circular Motion, or Rotation, arifes purely from the Reliftance of the Ground whereon it is applied. Now this Re- liftence is equal to the Force wherewith the Wheel is drawn in the Right Line; inafmuch as it defeats that Direction ; Ofconfe- quence the Caufes of the two Motions, the one Right, the 0- ther Circular, are equal, and therefore their Effects, ;. e. the Motions are equal. And hence, the Wheel defcribes a Right Line on the Ground, equal to its Circumference.

For the Nave of the Wheel, the Cafe is otherwife.— 'Tis drawn in a Right Line by the fame Force as the Wheel, but it only turns round becaufe the Wheel turns, and can only turn with ir, and at the fame time therewith. Hence it follows that its Circular Velocity is lefs than that of the Wheel, in the Ratio of the two Circumferences; and therefore its circular Motion is lefs than its Rectilinear one.

Since then it neceffarily defcribes a Right Line equal to that of the Wheel, it can only do it by fliding, or what they call the Morion of Rafon.— That is, a Part of the circular Nave cannot be applied to a Part of a Right Line greater than it felf, but by Hiding along that Part; and that more or lefs, as the Part of the Nave is lefs than that of the Circle. See Rolling and Sliding.

Rota, is alfo ufed for a particular Court or Jurifdiction in Rome, eibblifhed for taking Cognizance of Beneficiary Matters, &c. See Benefice, &e.

The Rota con (ids of twelve Doctors, chofen out of the four Nations of Italy, France, Spain, and Germany $ three of them, be- ing Romans, one a Florentine, one a Milattexe, one of Boulogne^ one of Ferrara, one a Venetian, one a Frenchman, two Spaniards, and one a German; each having four Clerks or Notaries unaer him.

Their Office is to judge of all Beneficiary Caufes, both in Rome, and the State of the Church, in Cafe of Appeal; and ; of all Civil Proceffes, of above 500 Crowns.

They are alfo called Chaplains of the Pope, as fucceeding the antient fudges of the Sacred Palace, who held their Court m his Chapel.

The Name Rota, WfcSe% fome will have derived hence, that they officiate each in his Turn; others, becaufe the molt impor- tant Affairs of the Chriffian World turn upon them. — Du Cange derives it from Rota Vorphyretka, becaufe the Pavement of the Chamber where they formerly fat was of Porphyry ; and fafhioned like a WheeL

ROTATION, Rolling, in Mechanicks. See Rolling, Rota, <&c

Rotation, in Geometry, the Circumvolution of a Surface round an immoveable Line, call'd the Axis of Rotation, See Axis.

By fach\Rotation of Planes, Solids are form'd or generated. See Genesis, Solid, <&c.

The Method of cubing Solids, generated by fuch Rotation, is well laid down by M, de Moyvre, in his Specimens of the ufe of the Doctrine of Fluxions.— For the Fluxions of k fuch Solids take the Product of the Fluxion of the Abfciffa, multiplied by the circular Bafe; and fuppole the Ratio of a Square to the Cir- cle inferibed, be as - : The Equation exprefting the Nature or Property of any Circle, whofe Diameter is d; is yy=dx— xx. Therefore 4 xx x x is the Fluxion of a Portion of the Sphere, and confequently, the Portion it felf ^xdx—\x*, and the cir- cumfcribed Cylinder is ■■ ** * therefore the Portion of the

Sphere