Note 7 — SECTION V. Of Single Fire-Works.

The force by which this wheel revolves is very remarkable, as it unites in itself those two adverse forces which have been the subject of so much mathematical controversy, namely, the centrifugal and centripetal: it may appear like trifling with science to observe these forces in this simple production, but that they do exist in it is not less evident: for from the revolutions of the ignited particles of the composition the former is produced, and from the nature and well known properties of the evolute curve, cæteris paribus, the latter is produced.

The Evolute and Involute Curves are possessed with many remarkable properties, which it would be no difficult task to unfold, but as it could be of no practical use to the Pyrotechnist, we shall leave it to such of our Mathematical readers as are able to appreciate the pleasure which such investigations afford. And for their assistance we refer them to the excellent writings of Hutton, Simson, Maclaurin, &c. And to Sect. 4, Book 2, Newton’s Principia, where they will find the subject beautifully illustrated.