NEW 
was capable of being applied to the greateft purpofes. 
Upon this he drew up about a dozen propofitions relating 
to the motions of the primary planets round the fun, 
which were communicated to the Royal Society towards 
the latter end of the year 1683. Thefe propofitions ex- 
ercifed the ingenuity of the greateft mathematicians, and, 
among others, of Dr. Halley, who found himfelf unable, 
as well as the reft, to carry the demonftration of them 
through all the particulars. Thus baffled, he made a 
journey to Cambridge in Auguft 1684, in order to con- 
fult our author, who informed him that he had abfo- 
lutely completed the proof; which he tranfinitted to him 
in the month of November.- Dr. Halley now paid the 
author a fecond viiit, and obtained his confent, though 
not without difficulty, that his demonftration Ihould be 
entered in the regifter-books of the Royal Society. After 
this, our author was prevailed upon, by the importunity 
of Dr. Halley, and the requeft of the fociety, to proceed 
to the completion of his Principia. The third book of 
that work, being only a corollary of fome propofitions in 
the firft, was then drawn up by him in a popular way, 
with the intention of its being publiffled in that form ; 
but he was afterwards convinced that it was belt not to 
let it appear without ftriCt demonftration. At length the 
work was printed under the care of Dr. Halley, and was 
publi&ed about midfummer 1687, under the title of, “Phi- 
lofophise naturalis Principia Mathematica,” quarto; con¬ 
taining, in the third book, the Cometic Aftronomy, which 
had been lately difcovered by him, and was now firft given 
to the world. This treatil’e, full of fuch a variety of pro¬ 
found inventions, was compofed by him, from l'carcely any 
other materials than the few propofitions above mentioned, 
in the fpace of one year and a half. The fecond edition of 
it, with confiderable additions and improvements by the 
author, was printed at Cambridge in 1713, in quarto. 
Another edition, with Hill further improvements by the 
author, was publiflred at London in quarto, tinder the 
care of Dr. Henry Pemberton ; and was reprinted at 
Paris, with large notes, in four volumes, quarto. 
This great work, in which the author has ereCted a new 
fyftem of natural philofophy upon the bails of the molt 
fublime geometry, did not at firft meet with all the ap- 
plaufe to which it was entitled. One reafon for this was, 
that Des Cartes had then got full poffeffion of the world. 
He had rendered his philofophy agreeable to the imagi¬ 
nation, and adapted it to common conceptions: it there¬ 
fore met with a very general reception. Newton, on the 
other hand, with an unparalleled force of underftanding, 
had purfued nature to her molt fecret abodes, and was in¬ 
tent to demonftrate her refidence to others, rather than 
anxious to point out the way by which he had arrived at 
it himfelf. He finifhed his piece in that elegant concife- 
nefs, which had juftly gained the ancients an univerfal 
efteem. In faCt, the confequences in the work flow with 
fuch rapidity from the principles, that the reader is often 
left to fupply a long chain to conneCt them. It required, 
therefore, fome time before the world could underftand it. 
The beft mathematicians were obliged to ftudy it with 
care, before they could make themlelves mafters of it; 
and thofe of a lower order durft not venture upon it, till 
encouraged by the teftimonies of the more learned. But 
atlaft, when its worth came to be fufficientiy known, the 
approbation which had been fc llowly gained became uni¬ 
verfal ; and nothing was to be heard from all quarters, but 
admiration of what feemed to be the produdtion of a ce- 
leftial intelligence rather than of a man. “ Does Mr. 
Newton eat, or drink, or deep, like other men ?” fiiid the 
marquis de l’Hofpital, one of the greateft mathematicians 
of the age, to the Englifh who vilited him : “ I repre- 
fent him to myfelf,” he added, “ as a celeftial genius, 
entirely difengaged from matter.” 
Not long before the time when this work was fent to the 
prefs, the privileges of the univerfity of Cambridge were 
attacked by king James II. who fent a mandamus to ad¬ 
mit father Francis, an ignorant benediftine monk, to the 
Voj*. XVII. No. 1159. 
TON. 33 
degree of M. A. On this occafion, Newton appeared 
among the molt zealous and aCtive defenders of the right* 
of that body ; and was appointed one of the delegates to 
the high-commiffion court, where they maintained their 
caufe with fuch refolution and fteadinefs, that the king 
thought proper to drop the affair. Our author was alfo 
chofen one of the reprefentatives of the univerfity in the 
convention-parliament of 1688, the feffions of which he 
attended till its difiblution. In the fame parliament fat 
Mr. Charles Montague, afterwards earl of Halifax, who 
had been educated in the fame college with Newton, and 
was well acquainted with his abilities and merit. That 
gentleman, having been appointed chancellor of the ex¬ 
chequer, undertook the great work of re-coining the 
current money of the nation ; and, knowing no perion io 
well qualified to conquer the difficulties attending it as 
our author, obtained for him, in the year 1696, the office 
of warden of the mint. In this fituation he rendered very 
important fervice to the nation, and was very properly 
rewarded, three years afterwards, with the appointment 
of mafter of the mint, a place worth from twelve to fifteen 
hundred pounds a year, which he held during the re¬ 
mainder of his life. Upon this promotion, he appointed 
Mr. William Whifton, of Clare Hall, his deputy in the 
mathematical chair at Cambridge, allowing him the entire 
profits of the place; and, about four years afterwards, he 
procured him to be his fucceft'or in that poll. In 1.699, 
the Royal Academy of Sciences at Paris having made. a. 
new regulation for the admiffion of foreigners into their 
fociety, lie was immediately elected a member of it; and 
in 1703 he was chofen prefident of the Royal Society, and 
retained that honourable ftation till the time of his death. 
In the year 1704, Newton publiflied, at London, his 
“ Optics; or, a Treatife of the Reflections, RefraCtions, 
Inflexions, and Colours, of Light;” quarto. This work 
is the refult of his occafional labours for thirty years, in 
bringing the experiments on which his “ New Theory of 
Light and Colours” is founded to that degree of certainty 
and exaCtnefs, which alone could fatisfy himfelf; and, in 
faCt, this feems to have been his favourite invention. In 
the fpeculations concerning infinite feries and fluxions, 
and the power and rule of gravity in preferving the fblar 
fyftem, there had been fome, though dillant, hints given 
by others before him ; but he was abfoluteiy the firft per- 
fon who conceived the idea, and engaged in the fubtle and 
delicate ftudy, of the anatomy of light, who diffeCted a ray 
of light into its primary conftituent particles which then 
admitted of no furtherfeparation ; who difcovered the dif¬ 
ferent refrangibility of the particles thus feparated, and 
that thefe conftituent rays had each its own colour inhe¬ 
rent in it; that rays falling in the fame angle of incidence 
have alternate fits of reflection and refraClion ; that bodies 
are rendered tranfparent by the minutenefs of their pores, 
and become opaque by having them large; and that the 
moft tranfparent body, by having a great thinnefs, will 
become lei’s pervious to the light. However, what had 
thus employed his affiduous researches for fo many years, 
was far from being confined to the fubjeCl of light alone. 
On the contrary, it feemed to comprehend in it all that 
we know of natural bodies. He had difcovered, that 
there was a mutual aCtion at a diftance between light and 
other bodies; by which both the refleClions and refrac¬ 
tions, as well as inflections, of the former were conllantly 
produced. To afcertain the force and extent of this prin¬ 
ciple of aCtion, was what had all along engaged his 
thoughts, and what, after all, by its extreme l’ubtlety, 
efcaped even his molt penetrating fpirit. But, though he 
has not made fo full a difcovery of this principle, which 
direCts the courfe of light, as he has of the power by 
which the planets are kept in their courfes; yet he has 
given the beft directions poffible for thofe who may be 
difpofed to carry on the work, and furnilhed abundant 
matter to animate them to the purfuit. By this means he 
has opened a way of palling from optics to an entire fyftem 
of phyfics i and, if we look upon his queries as furnilhing 
Kr us 
