Pyrotechnia or, A discourse of artificiall fire-works in which the true grounds of that art are plainly and perspicuously laid downe: together with sundry such motions, both straight and circular, performed by the helpe of fire, as are not to be found in any other discourse of this kind, extant in any language. VVhereunto is annexed a short treatise of geometrie, contayning certaine definitions and problemes, for the mensuration of superficies and sollids, with tables for the square root to 25000, and the cubick root to 10000 latus, wherein all roots under those numbers are extracted onely by ocular inspection. VVritten by Iohn Babington gunner, and student in the mathematicks.

CHAP. XV. How to compose a wheele.

NOW I will shew you the order of composing a wheele, which is a prime work, being well ordered; of which some are movable, and some immovable: of the mo∣vable, some move horizontall, and some verticall, which is toward the zenith: and first of the movable wheele. You must provide a wheele of such diameter as you please, which must be made into squares, according to the circumference of your wheele, and to proportion your wheele into a just number, you may allow five inches or better for every side, so that your wheele being 14 inches diameter, the circumference will be as 7 to 22, which is 44 inches circumference; so being divided by 5, there will bee 8 squares, or more properly, 8 sides, which will every one containe 5 inches and 3/10, which is the cord of 45 degrees; these sides must bee hollowed with a groofe fitting your rockets, and at the ends of every side it must bee filed with notches, to fasten your binding that it slide not, when you binde fast your rockets; the form whereof you shall finde in the fift figure N 1.

• A Sheweth the 8 sides.
• B The places of fastning.
• C The screw which fastneth the wheele to some post.

Note alwayes, that as your wheele doth increase in diameter, so you must increase in the proportion, for that rocket which forces about a wheele of 14 inches, will not force a wheele of 18 inches; nor that roc∣ket which forceth one of 18 inches, will not force one of 24 inches; but that you may come to a neere proportion, I will satisfie you so neere as I can; first seek the diameter of your wheele, which imagine to bee 18 inches, I take the third thereof, which is 6, so that your rocket for 18 inches diameter, must be 6 inches long, and your wheele of 24 inches diameter, will require rockets of 8 inches; yet as your wheele encreaseth, you may alter this proportion by dividing it into more sides.

Now having provided your wheele, with your rockets of a just size, you shall proceed to the finishing of it, which must bee after this man∣ner; you must joine your rockets one to another, in such sort as I shew∣ed you for your runners, that is, with the mouth of the one to the top of the other, and so proceed till you have fastned so many as will serve your wheele, alwayes leaving so much space between each rocket, as may suf∣fer them to come round about your wheele, without breaking any; which when you have done, proceed to the tying of them on to your wheele, which must be so ordered, that you tie them where the notches are, to the end they faile not in firing, by sliding off. In tying the•••• on you must provide that you leave a little distance between the first and the last, which must be parted with a bolster of paper well soaped, to th••

end that the first fire not the last, and so cause a great confusion. Now for the manner of placing them, it is according to the workmans plea∣sure, which must be either horizontall, or verticall; for the horizontall wheele you must provide a post fastned in the ground, and screw your wheele to the top of it; for the verticall, you must screw it on the side of the post, so having fired them, you shall see one run parallell to the ho∣rizon, and the other to the zenith, as you shall see described in the fift figure.

• N 2 Representeth the horizontall wheele.
• N 3 Representeth the verticall wheele.

There are many other works which do wholly depend upon the wheele, of which I will set down some few.

Notes

• Figure 5. N 1.