1 TS On the Catoplrical and Dioptrical 



nealogies, and intrigues, and torturing, and throat-cutting, 

 and desolation ; to which we must now add, the late im- 

 provements in poisoning and guillotining. It is, indeed, 

 no wonder that such scenes should have provoked honest 

 Dr. Johnson to brand historv in general with the name of 

 ** The Annals of Blood." But I cannot stop to moralize. 



3. Before I proceed to Abat, however, I must lay before 

 the reader a passage which I have found since writing mv 

 last (in Heathcote's Hisloria Astronomies, p. 41), and which 

 comes very properly into this place. " Wood in Historia, 

 &c. Woody in his Universal History of Oxford, book i. 

 p. 122, hath extracted a passage from a manuscript book 

 of Roger Bacon, De Perspectivis, in which he appears to 

 own that the invention of the optical tube is much more 

 antient than his days. For he writes (Julium Ccesarem, 

 tubi ope, a Gallicano littore, partus Anglice, urbesqite ma- 

 ritimos spectasse, cum helium in Britannos meditaretur) 

 that Julius Ccesar, by the help of a tube, viewed, from the 

 coast of Gaul, the ports and maritime towns of England, 

 when he meditated a war against the Britons." Here there 

 is not, any more than in Bacon's words to the same effect, 

 which I translated, at § 25, of my last, any mention of 

 iC raising up speculums to a great height," as Dr. S. would 

 have it, in order to make' Bacon's glasses entirely fixed and 

 stationary. Yet, if Ccesar used telescopes, it is natural to 

 think that he would carry them to the highest ground, or to 

 the speculce, or watch-towers, which were erected along the 

 narrow part of the British channel, and of which one 

 lately existed at Dover. All that I would be understood to 

 mean is, that, as far as I can find, Bacon did not suppose 

 that Ceesar's instrument was necessarily fixed to a spot. 



4. Be this as it may, Bacon's belief of this story of Julius 

 Ccesar' s optical tube," seems to be no bad proof of the ex- 



A. D. 1*67; and that there were only three persons then in England 

 who had made any considerable proficiency in that tcitnee. Friar Bacon, 

 was one of those three j and that he had made great proficiency in it, we 

 have the clearest evidence still remaining in his admirable treatise De Sci- 

 entific Perspective*" — " In a word, there is the clearest evidence, in the 

 .works of this wonderful man, that he was acquainted with the construc- 

 tion of all the different kinds of instruments for viewing objects to advan- 

 tage, which have been so much admired as modern inventions." Hist. 

 of G. Brit. 2d ed. vol. viii. p. 198, 200, where the learned author quotes 

 A. Wood Hist. Oxon. lib. i. p. 122; and Ola Borrick, De Ortu et Prog. 

 Cbem. apud Mangct, Bibliotb. Cbem. t. i. pp. 31 and Coo. Was not John 

 Pcrcam^ archbishop of Canterbury, who wrote a hook on optics in 1279* 

 about nine vears afrer the celebrated t'ole Vitellio wrote his, cne of the* 

 three English opticians here mentioned by Dr. Henry? — Fid. Woljii Elem* 

 Math. Univ. t. V. p. 95. 



cellence 



