C 458 ] 

 CHAP. IV. 



BURNING M1URORS. 



1 HE fertile genius of Archimedes illustriously appears, not only 

 in those works of his w hieh have been handed down to us, but also 

 in the admirable inscriptions which the authors of his time have 

 given us of his discoveries in mathematics and mechanics. Some 

 of the inventions of this great man have appeared so far to surpass 

 human ability and imagination, that some celebrated philosophers 

 have called them in question *, and even gone so far as to pretend 

 to prove their impossibility, The following pages will produce 

 many proofs of what is here advanced : meanwhile, our present ob- 

 ject is to examine into the subject of the burning glasses, employed 

 by Archimedes to set fire to the Roman licet at the siege of Syra- 

 cuse. Kepler, Naudeus, and Descartes, have treated it as a mere 

 fable, though the reality of it hath been attested by Diodorus Sicu- 

 lus, Lucian, Dion, Zonaras, Galen, Anthemius, Eustathius, Tzet- 

 zrs, and others. N.iy, some have even pretended to demonstrate 

 by the rules of catoptrics the impohsibility of it, notwithstanding 

 the asseveration of such respectable authors, whose testimony 

 eught to have prevented them from rejecting so lightly a fact so 

 well supported. 



Yet all modern enquiries have not been involved in this mistake. 

 Father Kircher, attentively observing the description which Tzetzes 

 gives of the burning glasses of Archimedes, resolved to prove the 

 possibility of this; and having, by means of a number of plain 

 mirrors, collected the sun's rays into one focus, he so augmented f 



Descartes in his Dioptrics, Discourse 8th, p. 128. Fontcm lie, and many 

 other. 



+ Kirrhrr, dc Ante Mi'gua Locis, ct Umbrae, lib. 10, p. 3. p. 874 nd tint in, 

 et Problem. 4, 3a part, de MagiA Catoptrica And p. 884, 887, he delivers 

 the catoptric rulr<. for making burning glasses l>\ a proper disposition of many 

 phiin mirrors. And in p. 88, relates an experiment of his own, whereby he pro- 

 duced a lip.il ini DM- enough to burn, by means of five mirrors directing the rajs 

 of the sun into one focus; he supposes that I'roclu-. by such means might set 

 fire to Vitdlios'g fleet, and invites tlic kkilful to bring this assay to perfection. 



