an Autograph Manuscript by Sir Isaac Newton. 71 



This manuscript bears no date, but two circumstances enable 

 me to state that it must have been written certainly eleven, and 

 in all probability fifteen, years before the publication of the se- 

 cond edition of the Principia in 1713. ls, The edition of 

 DAVID GREGORY'S Elements of Astronomy, into which, as already 

 stated, much of that portion of the manuscript which relates to 

 the opinions of the ancients has been transferred almost verba- 

 tim, was published in the year 1702. 3d, I find the whole of 

 the manuscript fairly copied, in the handwriting of DAVID 

 GREGORY, into the end of a manuscript book, containing his un- 

 published notes upon the Principia of NEWTON, and bearing a 

 running date from 1687 to 1697. In 1702 Sir ISAAC NEWTON 

 was not more than 60 years of age, and if, as appears almost cer- 

 tain, DAVID GREGORY received this manuscript from him between 

 1687 and 1697, he must have received it when NEWTON was be- 

 tween 45 and 55 years of age. 



I do not know whether it is true, as stated by HUYGENS, 

 " NEWTONUM incidisse in Phrenitin ;" but I think every gentle- 

 man who examines this manuscript will be of opinion that he 

 must have thoroughly recovered from his Phrenitis before he 

 wrote either the commentary on the opinions of the ancients, or 

 the sketch of his own theological and philosophical opinions 

 which it contains. 



Since the foregoing notice was read, some additional light has 

 been thrown on the points to which it refers, by the publication 

 of Sir ISAAC NEWTON'S Correspondence with Mr LOCKE, in the 

 Life of the latter by Lord KING. Two of NEWTON'S letters to 

 LOCKE, contained in this valuable work, might, at first sight, ap- 

 pear to favour the supposition of a temporary derangement in his 

 intellect, more especially as they correspond in point of date with 

 M. BIOT'S " fatal epoch" of 1693 ; and as NEWTON himself states 

 in one of them, that he had totally forgotten what he had writ- 



