Page:Cyclopaedia, Chambers - Volume 2.djvu/643

 ROC

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ROC

The Abbot Galleys, in the Memoirs of the Trench Academy, Ait. 1693. obferves, that the Method of transforming Figures, explain'd at the latter end of M. de Roberval's Treatife of Indiv't- fibles, is the fame with that iince published by Mr. J.nnes Grego- ry, in bis Umverfal Geometry ; and that, by a Lettet of Torricellh, it appears that Roberval had invented this manner of transforming Figures, by means of certain Lines which Torricelli called Rober- •vallian Lines.

He adds, that 'tis highly probable that J. Gregory firll learned the Method in the Journey he made to Padua in 166%; the Me- thod it felf having been known in Italy from the Year 164,6 ; Chough the Book was not publiflied till the Year 1692.

This Account Dr. David Gregory has endeavour'd to refute, in Vindication of his Brother.— His Anfwer is inferted in the Phil. Tranfacl. An. 1694. and the Abbot has rejoin'd in the French Memoirs of the Academy, An. 1703.

ROBIGALIA, or Rubigalia, in Antjquity. Sec Rubi- galia;

ROBORANTIA, in Medicine, Strengthmers ; or fuch Me- dicines as ftrengthen the Parts, and give new Vigour to the Con- ftitution. See Strengthened

ROCAMBOLES, a mild, pleating Sort of Garlick, by fome call'd Spanijb Garlick,- being much of the Nature of Shaloc^ and well known in Cookery, in Quality of a Sauce.

ROCHET, a Lawn Garment, wore by Bifhops and Abbots ; refembling a Surplice, except in this, that the Sleeves arc gather- ed at the Wrift ; whereas the Surplice is quite open. See Sur- plice.

The Regular Canons of St. Augufiin do alfo wear Rochets un- der their Copes.— Menage derives the Word from the Latin Ro- chettus, a Diminutive of Rocchus, ufedin the Writers of the lower Latin for Tunica^ and formed originally from the German, Rock.

Rochets are alfo the Mantles wore on Days of Ceremony, by the Peers fitting in the Lnglip Parliament. See Peer, and Parliament.

Thofeof Vifcounts have two Bands or Borders and a half 5 thofe of Earls three ; thofe of Marquiffss three and a half j and thofe of Dukes four. Larrey.

ROCK, Rupes, a large Mafs or Block of hard Stone, rooted in the Ground. See Stone.

There are various Ways of breaking Rocks with Wood, Gun- powder, $>c. See Quarry, Wood, &c.

We have Roads, Grotto's, Labyrinths, &c. dug through Rocks. See Road, Grotto, Labyrinth, &c.

The Word is form'd of the Greek e°%, Rhna, Cleft, Chink ; and t4 from gaym/atef, I break ^ whence £«*<«, a ftony River.

RocK-JPork, Rocaille. See Shell-^ 7 ^.

RocK-Cryftal, or Cryjlal of the Rock, is that form'd by a Con- gelation of the lapidific Juices which trickle down in Rocks and Caverns. See Crystal.

ROCKET, in Pyrotechnia, an artificial Fire-work, confiding of a cylindrical Cafe or Paper, filled with a Compolition of cer- tain combuftible Ingredients ; which being tied to a Stick, mounts in the Air to a coafidefable Heighth, and there burfts. See Pyrotechnia and Fire-Works.

The Rocket has a great Part in all Fire- Works of Entertain- ment, being not only ufed fingly, but fometimes, alfo, as an In- gredient in others.

Befldcs the Rocket here defined, which is properly calPd ihcS&y- Rocket, there is another, which from the Sphere it moves in, the Water, is denominated Water-Rocket. — The Mechanifm, Prepa- ration, &c. of each whereof, we mall here defcribe.

Method of making a 5^-RocKET.

i°. A Concave cylindrical Mould,' or Frame, AB, Tab. Mfcel- lany, Fig. 7. is turn'd, of hard Wood, with a Bale BD, and a Capital HC, ufually adorned with architedtonical Mouldings.— The Cylinder is to be open at both Ends, and its Dimentions, for Rockets of various Sizes, as in the following Article.— When large, they are fometimes alfo made of Brafs or Tin ; and when fmall, of Bone.

2 . Of the fame Matter with the Cylinder, is prepared a Qua- dra, or Foot E ; in the middle whereof is turn'd a Hemifphere G, confiderably lefs than that of the Cavity of the Frame; ma- king the Cap or Head of another Cylinder IK, and reaching up within the Cafe; where 'tis kept fteady by a Pin LM.

Authors don't agree about the Proportions.— Smimnaitz pre- scribes thofe that follow. If the Diameter of the Aperture HN be equal to that of a Leaden-Ball of a Pound, or at mod two Pound Weight; the Heighth of the Cylinder, with the Bale and Capital HC, are to be feven Diameters of theHeighth of the Qua- dra FE i '. The Altitude of the Cylinder KI, 1. TheDia- xneter IN £|. The Diameter of the Hemifphere G, f. The Heighth of the Capital AC, 1.— The fame Author adds, that he finds by abundant Experience, that if the Diameter of the Aper- ture be divided into 100 Parts, according to $he different Weight

of the Leaden-Balls to whofe Diameter 'tis equal, the following Numbers being multiplied by 7 give the Heighth HE.

Weight of

Subfeptuple of

Weight of

Subfeptuple of

Leaden-Ball

Altitude HE.

Leaden-Ball.

Altitude HE.

1

100

20

86

2.

98

30

82

4

26

40

"8

6

9+

5°

75

10

9 l

7°

<>7

1$

88

100

57

TheFrame being ready, a wooden Cylinder orMould AB (Fig.S.) is provided, whole Diameter is > of the Aperture of the Frame, and its Length equal to the Heighth of the fame; to which isa- fix'd a Haft or Hilt AD. About this Mould is a thick ftrong Pa- per roil'd, 'till fuch time as it fill the Cavity of the Frame. This done, where the Haft is join'd to the Cylinder, as at A, 'tis choak'd, i. c. firmly bound round with fine Pack-thread, fo as to conftringe or ftraighten the Cavicy thereof.— The Part thus cboak'4 or bound up FG, (Pig. o.J to be equal to the Hemifphere G.

The Cale is now taken off the Mould, and put into the Ca- vity of the Frame, Fig. j. the Chunk GP upon the Hemifphere-, and in this Difpolition is fill'd with a Compolition defenbed in the following Article, ramm'd ftrongly in by means of a wooden Cylinder or Rammer fitting the Cavity, and a Mallet. ^ When fill'd, a Paper Cap of a conical Form is glued over the End of the Cafe fill'd Iaft ; and the Space left a-top fill'd with whole Gun-powder, to the Heighth of about one Diameter; then the Rocket bound, or choak'd in E, as before in G.

Laftly, the Rocket is bored, as is reprefented in «L Eg. 9. care

being taken to do it in the middle Some, indeed, bore the

Rocket as they fill it, by thrufHng a long, (harp Spike through the lower Balis, and drawing it out again when the Rocket is full : But 'tis bell: not to bore till the Rocket be to be ufed.

The boring is to go two thirds of the Heighth of [he Rocket, a- bating one Diameter of the Cavity. The Diameter of the Bore in G is to be i of the Diameter of the Cylinder; and in L J. of the lower Diameter.

To make the Rocket mount ftraight up, it is tied faff to the End of a long flender Stick, MN, eight times as long as the Rocket ; in fuch manner as that when poiz'd on the Finger near the Touch-hole F, the Stick (which is ufually made biggeft at this End, and Hoping gently to the other) may preponderate, tho* very little.— The Rocket thus equip d, is hung at" freedom, and lighted with Pott-Fire.

Note, Some inftead of a Stick to make the Rocket mount, fiir- nifh it with two Wings, as MN, (Fig. 10.) which have the fame Effect : And inftead of Paper lomc make the Cafes of Wood, covcr'd with Leather; others of a thin Iron Plate. And tome, inftead of a wooden Stick ufe an Iron Wire, with a Plummet at the end of it.

The Compolition wherewith Rockets are fill'd, coniiirs of the three following Ingredients, viz. Saltpetre, Charcoal, and Sul- phur; all well ground : But the Proportions of thele are various for Rockets of various Sizes; as in the following Table. Noting, that in fmall Rockets Gun-powder Duft is added.

Compactions for RoclCETS of various Sizes.

Weight of

Salt-

Sul-

Char-

Gun-powder

Rocket.

pet:

phur.

coal.

Duft.

lb

it

lb

It

100, or 60

30

10

20

50 30

30

7

18

20 18

V-

12

z6

15 12

=3

8

16

10 9

62

9

20

9 6

35

5

10

5 4

64

8

16

3 2

So

2

15

1

1 ^

1 6

3^

Ounces.

Oun.

Oun.

Ounce.

Ounc.s.

9

4

1

2

9

6

12

\\

4

15

3

2

T

ii

12

1

2

'5

Note, feveral Rockets being difpofed round the Circumference of a Wheel, whether Circular or Polygonous, the Head of the one applied to the Tail of another, and the Wheel put in Moti- on ; as one Rocket is fpent another will take Fire : And the Wheel be continued in its Rotation.

As an additional Ornament to Rockets, 'tis ufual to furnifh them either with Scars or with Serpents, or Sparks, which take Fire when the Rocket burfts : And fometimes little Rockets are inclofed