Page:Cyclopaedia, Chambers - Volume 2.djvu/644

 ROE

( 1027 )

ROL

in great ones, to take Fire when the great one is at its greateft Heigbth.

To make Stars for Rockets.

Mix 3 Pound of Salt-petre, with 11 Ounces of Sulphur, 3 Ounces of beaten Gun-powder, and 10 of Antimony* Moiften the Mafs with Gum-Water, and form it into little Balls of the Size of Filberds ; drying them well, either in the Sun or an Oven. When dry indole a Number of them in the Conical Cap of the Rotket.

Method of making a Water-RocYLET.

Make a Rocket AB after the ufual Manner, excepting in the Number of Cboaks, exprefi'd in Fig. 11.— Let its Diameter be equal to that of a Leaden-Ball of two or three Inches Diameter, and let it be bored to a third Part of its Heighih. Inclofe the Rocket in a hollow Paper Cylinder ; which linear over with melt- ed Pitch or Wax, that it may reiiii the Moifture.

Note, The Weight of the Rocket is to be fo proportioned to that of the Water, that the whole Cylinder may be immerg'd. —Some inftead of a Cylinder ule a truncated Cone, or even a Spheroid; and fome hang a Weight to the End at which 'tis lighted.

Theory of the Flight of %-Rockets.

Mariotte takes the rife of Rockets to be owing to the Impulfe or Refiftance of the Air againit the Flame: Dr. Defaguliers ac- counts fur it otherwife.

Conceive the Rocket to have no vent at the Choak, and to be fee on Fire in the conical Bore ; the confcquer.ee wond be, ei- ther that the Racket wou'd burll in the weakeft Place, or that, if aU its Parts were equally ftrong and able to fuftain the Impuife of the Flame, the Rocket would burn out immoveable.— Now, as the Force of the Flame is equable, iuppofe its Action downwards, cjr that upwards fufficient to lift 40 Pounds. As chefe Forces are equal, but their Directions contrary, they will dettroy each other's Action. See Action and Reaction.

Imagine, then, the Rocket open'd at the Choak; by this means the Action of the Flame downwards is taken away, and there re- mains a Force equal to 40 Pounds acting upwards, to carry up the Rocket, and the Stick it is tied to.— Accordingly, we find that if the Compoiition of the Rocket be very weak, fo as not to give an Impulfe greater than the Weight of the Rocket and Stick, it does not hie at all : Or if the Compofition be flow, fo that a fmall Part of it only kindles at firft, the Rocket will not rife.

The Stick ferves to keep it perpendicular : For if the Rocket mould begin to tumble, moving round a Point in the Choak, as being the common Centre of Gravity of Rocket and Stick, there wou'd be Co much Friction againit the Air, by the Stick between the Centre and the Point, and the Point wou'd beat againit the Air with fo much Velocity, that the Reaction of the Medium wou'd reftore it to its perpendicularity.

When the Compoiition is burnt out, and the Impulfe up- wards is ceas'd, the common Centre of Gravity is brought low- er, towards the middle of the Stick; by which means the Velo- city of the Point of the Stick is decreafed, and that of the Point of the Rocket incrcas'd : So that the whole will tumble down, with the Rocket-cod forenioft.

All the while a Rocket bums, the common Centre of Gravity is ihifting and getting downwards, and Hill the falter and the low- er as the Stick is the lighter : So that it fometimes begins to tum- ble* e'reit be burn'd out: But, when the Stick being a little too heavy, the Weight of the Rocket bears a lefs Proportion to that of the Stick, the common Centre of Gravity will not get fo low, but that the Rocket will rife {trait, though not fo fait.

ROD, V1R.GA, Verge, a Wand, or long {lender Stick or Staff. See Verge, Staff, &c.

Rod, is alfo a Land-Meafure of 16 Foot i> the fame with Perch and Role. See Perch and Pole.

Rod, in Gauging. See Gauging-TcW.

KoD-Knights, in ancient Cuftoms. Sec Redmans.

Black-Roo. See Black- JcW,

ROE, of a Fifh, is that Part which contains the Sperm or Seed thereof. See Fish, Seed. &c.

That of Male-Fimes is I'ufually diftinguifhed by foft Roe, or Mih\ that of the Female by hard Roe.

The ibft Roe when fqueez'd, yields a Liquor refemblingikfaft; whence its Name Milt : The French call it expreily Milk-, laite. See Milt.

That of Carps is efteemedan excellent Food.— M. Leewen- hocck upon examining the Milt of a Cod-FhTi with a Microfcope, found it contained more living Animalcules than there are Men in the whole Earth. See Egg, Animalcule, Microscope, &c.

Roe, one of the Beafts of Chafe. See Beast and Game.

Roe-Bba&. See Hunting.

Roe-B/ff*, a Beaft of Chace or Foreft. See Beast, Game,

The Roe-Buck is called an Hind the firft Year; Gjrle the £■* cond ; Henufe the third ; Roe-Buck of the fir 11 Head the fourth ; and a fair Roe-Buck the fifth.

The Roe-Buck is a Deer well known in Germany ; and feems to have alio been formerly known in England, though now the Race be extinct. See Hunting.

ROGA, in Antiquity, Donatives, or Prefencs which the Au- gttfti or Emperors made to the Senators, Magistrates, and even the People; and the Popes or Patriarchs to their Clergy. See Donative.

The Emptors ufed to diftribute thefe Roga on the firit Day of the Year, or on their Birth Day; or on the Natalis Dies of the Cities— The Popes and Patriarchs in Paflion Week.

This Ciiftoni of Roga } orLargefles, was firft introduced by the Tribunes of the People, to gain the Populace more effectually over to their Interelt. The Emperors at length took it up, and made fuch Diftributions to the People, and even the Soldiery, call'd by the Greek Writers in the middle Age POrATOPES.

Rogum is alfo found ufed for the ordinary Pay of the Sol- diery.

The Word is derived by fome from the Latin erogare, to give, diftribute; according to others from rogo, I ask; hence, fay they, it is that St. Gregory the Great calls fuch Diftributions Precaria- 7 as being to be demanded, in order to be had. See Precari^e-

Others, again, derive it from the Greek pay©*, Corn ; becaufe it antiently confifted in Corn diftributed among thcPopulacc, the , Soldiery, &c.

ROGATlOjin the -Rowa» Jurisprudence,* a Demand made by the Confuls, or the Tribunes, of the Roman People, when a Law was pfopofed to be pafj'd. See Law.

The Demand was made in thefe Terms ; Do you will and ap- po'mt that (for Inftance) War be declared agamfi Philip ? This was i\\z Rogaiio ; and what the People rerurn'd in anfwer, as, The Ro- man People do appoint War to be made again}} Philip, was the De~ cretum, Decree.

However, the Word Rogaiiq is frequently ufed for the Decree it felf; to diftinguifh it from a Decree of the Senate. See Decree.

Frequently, alfo, Rogation is ufed in the fame Senfe with Law- becaufe there never was any Law eftablithed among the Romans, but what was done by this kind of Rogation. — Other- wife it had been null. See Law.

ROGATION -Week, the Week immediately preceding- Whit- funday ; thus call'd from three Fills therein, viz. on the Monday^ Tuefday, and Wednefday, call'd Rogations, or Rogation Days, becaufe of the extraordinary Prayers and Proceffions then made for the Fruits of the Earth. See Procession.

The firft who appointed thefe Rogations was St. Mammercus, Bifhop of Vienna, who in 474 affembled feveral Bilhops, to im- plore the Mercy of God by a Fart of three Days; on occafion of an Incurfion then made upon the Country by a great Number of wild Beafts. — Others fay, 'twas firft Cct on Foot by Mammer- cus in 468, on occafion of fome publick Calamities.

ROGUE, in Law, an idle and fturdy Beggar; who for the firft Offence is called a Rogue of the firfi Degree ; and pun ftfd by whipping, and boring through the Griftle of the Right Ear with a hot Iron, an Inch in Compals: And lor the tecond Offence is call'd a Rogue of the fecond Degree, and put to Death as a Felon, if he be above eighteen Years of Age. See Felon, &c.

ROLL, in the Manufactories, lbmething wound or folded in a Circle. See Rolling.

Few Stuffs are made up in Rolls, but Satins, Gawfcs, and Crapes, which are apt to break, and take Plaits not eafy to be got out if folded otherwife. — Ribbonds, however, and Laces, Galloons, and Padua's of all Kinds, are thus roll'd.

To Roll hot— By an Arret of Council in 165)8, Fullers, Shear- men, &e. in Portion, are prohibited to Roll any Stuff hot, either by having Fire over or under it, or by heating the Rollers, or otherwife, on Forfeiture of 100 Livres for the firft Offence; or of being degraded from the Privileges or Malterihip in Cale of a Relapfe.

The Antients made all their Books up in Form of Rolls, or little Columns; and in Cicero's Time, the Libraries confifted wholly of iuch Rolls.— The dearnefs of Parchment, andthecheap- nefs of Paper, whereof the Rolls were made, were the Reafon that fcarce any but Paper Rolls were ufed. See Paper, Parch- ment, &c.

Vojjius fays, they patted fevejal Sheets end to end, when filfd on one Side, and roll'd them up together ; beginning with the laft, which they call'd Umbilicus, and to which they fattened an Ivory or boxen Stick, to fuftain the Roll. — To the other Extre- mity they patted a Piece of Parchment, to cover and preferve it. See Volume, Umbilicus, &c.

Thefe Rolls were placed in the Libraries, perpendicularly, to the Horizon. — The Je-ws ftill preferve the antient ufage of Rolls for the Books they read in their Synagogues. See Book-bind- ing.

ROLL of Tobacco, is Tobacco in the Leaf, twifted on the Mill, and wound Twiit over Twift, about a Stick or Roller.

The generality of Tobacco in America is there fold in Rolls,

of various Weights: And 'tis not till after its Arrival in England,

12 E Spain,