for the Defence of this Island. 35 



duced it to ashes. Proclus is recorded by Zonaras to have 

 destroyed the ships of VitaHan, besieging Byzaiitium (now 

 Constantinople), by a similar apparatas. The same tacts 

 are mentioned by other antient historians ; but their hints . 

 respecting the apparatus itself are too imperfect to afford 

 any ex])licit knowledge of its structure. But, as appears 

 from other passages of his life*, a very obscure hint was 

 sufficient to set in action the genius of Napier ; and the 

 foregoing memoir gives us every reason to believe that, put- 

 ting a happy construction on the words of Tzetzes, this 

 second Archimedes was the first among the moderns who 

 recovered this admirable invention of his illustrious pre- 

 cursor. So completely had it been buried in the wreck of 

 antient science, that Descartes, who certainly understood 

 at least the theory of optics better than any man of his 

 age, when he published his Dioptrics, above forty years 

 after the date of Napier's memoir, mentions the burn- 

 ing of bodies, at any considerable distance, by means 

 of mirrors, as an almost hopeless project, and scarcely 

 refrains from treating the famous exploit of Archimedes 

 as a fable f. Descartes was a great man, and therefore 

 his scepticism was, as usual, adopted by the common 

 herd, the serrum pecus, of philosophers, and even by some 

 men of real learning and ability. Of this last descrip- 

 tion was M. Ozanam, who says plainly that the catoptrical 

 achievement of Archimedes is incredible', and indeed not 

 ■without reason, if the distance really was (as he states it, 

 upon what autljorJty does not appear,) 375 geometrical. 

 paces, equal to 1875 French feet, or 2002 English 1". 

 This, it must be confessed, -seems to be giving too po~ 

 etical an in-terprctation to the bow-shot of the poet 

 Tzetzes. The justly celebrated Christian Wolfe seems 

 also disposed to give little credit to this curio;;s piece of 

 history; though he quotes father Kircher as having con- 

 cluded, from an actual survey of the site of the town and 

 harbour of antient Syracuse, that the distance to which 

 Archimedes had lo project the solar rays could not exceed 

 thirty paces §. This distance Is probably nearer the truth ; 

 at least it is more agreeable to our modern ideas aiid experi- 



'* See t!ie story of Dr, Craig in lord Buchan's eleg.iin Life of Napier, 

 and in Ur. Hutton's excellent Matlitm, and Philos. Dittiim. art. Ntyicr, 

 , + CiiTtcni Dioi'true (i.rst printed in 1657), cap. viii. sect. 22. 



\ bee M. Ozanam's Reaentions Maib. e! fhys., torn. i. p. 144, cd. 3. 

 Perhaps Dr. Mutton's Lite mucli improved translation of tins cunouj 

 work rniy affiird the rei 'er more satisfaction on this point. 



§ ^.lementa MuiLeifjs Univa;a-, torn. iii. p. i%%, 



D 4 mcnts. 



