VOL. XXX.] PHILOSOPHICAL TRANSACTIONS. 205 



Albionicis, p. 22,) that the word divisos may import the rending or breaking 

 off one thing from another ? And that Virgil knew its signification very well, 

 and was well acquainted with antiquity, and had not forgot himself? On these 

 words Servius says, " Because Britain was formerly joined to the continent." 

 Than which nothing can be more plain, than that the breaking through of this 

 isthmus was known to the ancients. 



Therefore, from the whole the Dr. concludes, that Britain was not originally 

 an island, but became such from a Peninsula; and that, as is probable, by the 

 concurrence of some one or other of the more boisterous winds with the tides, 

 and so breaking through the isthmus. 



Extracts from Mr. Gascoigne's and Mr. Crabtrie's Letters \ proving Mr. Gas- 

 coigne to have been the Inventor of the Telescopic Sights of Mathematical 

 Instruments, and not the French. By W. Derham, R.S.S. N° 352, p. 603. 



In M. de la Hire's first part of his Tab. Astron. published in l687, I find an 

 invention, which was undoubtedly our countryman's, Mr. Gascoigne, ascribed 

 to M. Picard, viz. the application of telescopic sights to astronomical instru- 

 ments. Mr. de la Hire's words are to this effect: " Some few years since M. 

 Picard, a great astronomer, and member of the Paris Academy of Sciences, 

 substituted telescopes instead of plain sights in astronomical instruments, &c." 

 In which words it is not indeed expressly said that M. Picard was the inventor 

 of this method, but only that he applied telescopes. But since it implies that 

 it was M. Picard's invention, and is in fact claimed as such, in M. Auzout's 

 Account of the Telescopic Micrometer, Phil. Trans. N°2], I think myself 

 bound to do Mr. Gascoigne the justice to assert his right to this invention; 

 because all his papers, which by the late Mr. Towneley's diligence could 

 be picked up, are now, together with Mr. Towneley's own papers, in my 

 hands. 



As for the invention of the micrometer, which Mr. Auzout claims as his 

 and M. Picard's, I shall say little to it, Mr. Towneley having sufficiently proved 

 it to be Mr. Gascoigne's, in the Phil. Trans. N° 25. And the descriptions and 

 draughts of that and some other instruments of the kind are now by me, in 

 Mr. Gascoigne's own hand, to confirm Mr. Towneley's account, if it were 

 necessary. 



And as Mr. Gascoigne was the first that measured the diameters of the 

 planets, &c. by a micrometer, so I shall prove that he was the first that applied 

 telescopic sights to astronomical instruments. In a long letter to his friend Mr. 

 Crabtrie, of Jan. 25, l640-l, in which he describes his micrometer, and shows 

 his way of finding the refractions, the moon's parallax, and how he measured 



