of the Earl of Macclesfield, and the papers belonging to the Royal Society. The first contain a number of Newton's own MSS., and having belonged to Mr. W. Jones are of indisputable authenticity; the second have indeed been often examined, but not so completely as to preclude some new facts being recovered from them by a repeated search. The extracts in the following tract sometimes vary from what has been printed by Birch in his History of the Royal Society: but the difference will be found not to affect the sense; and has been occasioned by the use of the originals, which he did not always copy verbatim.

For these last papers some references are used, which may not be obviously intelligible to every one, and any future examination may be facilitated by giving a short explanation of the different terms used to describe the arrangement of them.

The Journals contain an abridgment of the business transacted by the Society at large in their weekly meeting.

The Minutes are the records of what has

passed in the Council.

The Registers contain copies of the papers, which have been communicated.

The Letter Books preserve copies of letters, and, in some instances, of shorter papers, which have been drawn up in that form.

There are likewise original papers and letters, pasted into Guard Books, and arranged according to the initials of the writers' names.

The examination of collections, which lie so wide apart from each other, could only be undertaken by one, who was permanently resident in England: and, supported by this accidental advantage, I have sometimes ventured to differ from so able a writer as M. Biot. Truth, however, has been our common object, and it has always the best chance of being elicited by the fair statement of honest opinions.

It may be thought that the Essay is prolonged beyond its immediate purpose by what

is said, at the end, on the publication of the second and third editions of the Principia; but this, having been made as concise as possible, seemed to obviate what otherwise might appear to be an abrupt termination of the work; and it may not be without some use to those, who shall have the means and the inclination to continue this History to the time, when Newton set his last hand to the greatest work of his most powerful mind.

CORRECTIONS.

P. 19. lin. 14. "such oversights" add "(as, in this instance, of 1683 for 1684)”
P. 35. note f. for "III." read "IV."

P. 48. lin. 12. "which he adopted," add "in this correspondence with Hooke"
P. 49. lin. 8. "order of effect varied" read "this law of the effect ceased"
P. 78. head line. " Printing" read "Printing."

HISTORICAL ESSAY

ON

THE FIRST PUBLICATION

OF THE

PRINCIPIA.

DR. PEMBERTON tells us that the first thoughts, which gave rise to Newton's Principia, occurred to him when he had retired from Cambridge into Lincolnshire, in 1666, on account of the plague. Voltaireb had his information from Mrs. Catharine Barton, Newton's favourite niece, who married Conduitt, a member of the Royal Society, and one of his intimate friends : from having spent a great portion of her life in his society, she was good authority for such an anecdote, and she related that some fruit, falling from a tree,

a Preface to his View of Sir Isaac Newton's Philosophy. See Append. XII. p. 49. From Dr. Hodges's Aooλoyía, we learn that the plague began first in Westminster, at the end of 1664; that in London it was most violent in the hotter months of 1665, and had so far abated in the following winter that the inhabitants returned to their homes in December. The Royal Society did not indeed resume their regular meetings till March, 1666; but the disease had then subsided, and some writers have therefore referred Newton's speculation to 1665. Pemberton,

was the accidental cause of this direction to Newton's speculations. Conduitt himself drew up an account of facts, which he transmitted to Fontenelle, to form the foundation of the Eloge of Newton, which is inserted in the Histoire de l'Académie des Sciences, for 1727. This paper, in its original state, has been published by Mr. Turnor in his History of Grantham ; and it mentions the same circumstance. It was not noticed by the French writer, to whom it was at first communicated, but tradition marked the site of the tree from which the apple fell, till being decayed it was taken down about 1820, when the wood of it was carefully preserved. The anecdote indeed is neither devoid of interest, nor improbable in itself. He was sitting alone in a garden at the time, and one of the peculiar faculties of his powerful mind was to be able to follow out a chain of reasoning, in which the connecting links would escape the notice of a common observer. The tendency of bodies to fall towards the earth does not fail at the top of the highest mountains, and, as he was carried in thought to more remote regions, there appeared to be no assignable limit to its influence. He had found from the motions of the planets, that they were acted upon by a force towards the sun, which was reciprocally as the squares of their distances from it; and, as an experimentum crucis, he proceeded to examine whether the moon's motion would, in a circular orbit, agree with a similar variation; but the result of his calculations did not

At Woolsthorpe, where his mother lived. (Hist. of Grantham, p. 160). The farm is the property of Mr. Turnor, who has contributed his best endeavours to preserve the records of

Newton's family. His brother, the Rev. C. Turnor, of Wendover, has been likewise actuated by the same zeal for collecting what may be connected with the history of so great a man.