Instruments of the Anlients, 237 



quity of this invention stands established. I shall examine 

 it further on. Only I now remark, that the first author, as 

 far as I know, who held this opinion was father Kircher, 

 who, in his Ars magna Lncis et Umlrce, 1. x. p. 3. c. i* 

 prob.- 7, expresses his belief that Proclus, who lived in the 

 fifth century, used plane mirrors to burn the enemies' fleet 

 at the siege of Constantinople. Several authors have adopted 

 Kircher's opinion, not only with regard to the mirrors of 

 Proclus, but those also of Archimedes. All the learned, 

 before that reverend father, and several since his time, be- 

 lieved that all those anlient burning mirrors were parabolical. 



64. " This invention of plane burning mirrors is so fine, 

 and has for some years made so much noise in the learned 

 world, that it well deserves some detail of its history and 

 origin ; which will show that we do injustice to the ancients, 

 when we deny that they had this knowledge. 



65. ei Among the catoptricians of these last ages, father 

 Kircher was the first who asserted, that, with plane glasses, 

 it was practicable to compose burning mirrors superior to 

 any before known, &c* 



66. ?.f After Kircher, father Gaspard Schottus gave (in his 

 JMagia Universalis, torn, i.) the solution of a problem con- 

 cerning plane burning mirrors, in two different ways. He 

 has, however, done nothing more than copy the former, 

 without adding aught of his own, either in theory or prac- 

 tice. 



67. " It is astonishing that so fine an instrument, ex- 

 plained so neatly and precisely in the works of these cele- 

 brated men, which are well known to the learned, should 

 have lain dormant above a century, before any one, thought 

 of bringing it into use. Fontenelle, it is true, in his Eulogy 

 on Hartsoekerf, tells that this philosopher/ in his observa- 

 tory at Amsterdam, attempted a large burning mirror, com- 

 posed of several pieces connected together, like that, which, 

 according to some, was used by Archimedes. But M. de 

 Fontenelle does not tell us, whether or not those connected 

 pieces were plane mirrors, or what was the success of the 

 attempt. 



* Here my learned author goes on to sate, from Khcber, the facts 

 which I have already given, in my first letter (concerning Lord Napier's 

 Memoir, &c.) in vol. xviii. p. 53, &c. of this magazine. Almost the 

 only difference is, that he cites Kircher's Ars Magna Lucis et Umbra, 

 lib. 10. par. 3. p. 765, 771 et 772. edit. Amst. ; and I cite that father's 

 Magia Catoptrica, as quoted by Paulian. — Translator . 



t The celebrated Dutch philosopher, Har:soeker> died in the vear 17x5. 

 See Paulian' s Diction, de Physique, article Hartsoehr. — Translator. 



(38. « It 



