NEW 
cation of her fon Ifaac. At the age of twelve, fhe fent 
him to the grammar-fchool at Grantham, where he made 
a good proficiency in the languages, and laid the foun¬ 
dation of his future fiudies. Even in this place he gave 
early marks of his natural genius. “ Every one,” lays 
Dr. Stukeley, “ that knew fir Ifaac, or have heard fpeak 
of him here, recount the pregnancy of his parts when a 
boy, his Arrange inventions, and extraordinary inclination 
for mechanics ; that, inftead of playing among the other 
boys, when from fchool, he always bulled himfelf in 
making knicknacks and models of wood in many kinds; 
for which purpofe he had got little laws, hatchets, ham¬ 
mers, and a whole Ihop.” Gent. Mag. Nov. 1772. Of his 
infantine bias towards calculation and philofophical fub- 
je&s, the following trait is related: that he had then a 
rude method of meafuring the force of the wind blowing 
againft him, by obferving how much further he could leap 
in the direction ofthe wind, or with it blowing on his back, 
than hecould leap the contrary way, orin oppofition to the 
wind. After havingfpent a few years at Grantham, his mo¬ 
ther, who had no intention of educating him a fcholar or 
philofopher, fen t for him home, that he might betimes be in— 
itruCted in rural affairs, and rendered capable of managing 
his own eftate. But, inftead of minding the bufinefs ofthe 
farm, he was always ftudying or poring over books, and 
often by Health, without his mother’s knowledge. Being 
one day lent to market at Grantham, an uncle of his, 
who was a clergymen, difcovered him in a hay-loft, 
working a mathematical problem ; which circumllance, 
with what he had before obferved, fatisfied our divine 
that his nephew’s inclination for learning was invincible. 
He therefore perfuaded his mother to let her fon follow 
the bent of his mind, and to fend him back to the gram¬ 
mar-fchool. In 1660, when Ifaac was eighteen years of 
age, he was entered of Trinity-college in the univerfity 
of Cambridge, of which his uncle had been a member, 
and wherehe had ftill many friends. From the beginning 
of this century, particular attention had been paid in the 
univerfity to the ftudy of the mathematics, and the ele¬ 
ments of geometry and algebra had become generally one 
branch of a tutor’s leCtures to his pupil's. To thefe fciences 
Mr. Newton chiefly devoted his attention ; and by the 
uncommon force of his genius made fuch an extraordi¬ 
nary and rapid progrefs in them, that he excited the ad¬ 
miration and engaged the intimate friendfli'ip of Mr. 
(afterwards Dr.) Ifaac Barrow, at that time fellow of 
Trinity-college, and one of the moll eminent mathema¬ 
ticians of his day. The book with which he commenced 
his college-ftudies was “Euclid’s Elements;” but it did 
not detain him long, as he became mafter of the propo- 
fitions almoft as foon as his eye was run over them. 
Finding it fo plain and eafy to him, the youthful vigour 
of his underftanding would not fuffer him to fit down in 
order to contemplate the Angular excellence in that au¬ 
thor’s manner of demonftration, by means of which the 
whole feries and connexion of the truths advanced is 
continually kept in view' up to their firft principles. This 
negleCt, however, he was fenfible of in his riper years, 
and with great ingemioufnefs exprefled his regret to Dr. 
Pemberton, for his “ miftake at the beginning of his 
mathematical ftudies, in applying himfelf to the works 
of Des Cartes and other algebraical writers, before he had 
confidered the Elements of Euclid with that attention 
which fo excellent a writer deferves.” The truth is, when 
he firft went to college, Des Cartes’s analytical method 
was all in vogue ; to which therefore he particularly 
attended, as well as to Kepler’s Optics, Dr. Wallis’s 
Arithmetica Infinitorum, &c. making feveral improve¬ 
ments on them, which he inferted in marginal notes as 
he went along, according to his ufual method of ftudying 
any author. 
Dr. Wallis’s treatife more efpecially engaged Mr. New¬ 
ton’s notice, and prefented him with matter which fet 
his boundlefs invention at work, and opened the way 
into his “ New Method of Infinite Series and Fluxions.” 
X, 
TON. 31 
He was thus employed till the year 1664, when he took 
the degree of B. A. About this time, obferving that 
many ofthe moft eminent mathematicians were engaged 
in the bufinefs of improving telefcopes, which was a 
matter of much importance to the philofophical world, 
he defifted for a time from the purfuit of mere abftract 
fpeculations, and turned his thoughts to this more ufe- 
ful fubjeCt. Des Cartes, in his Dioptrics, affuming the 
commonly-received notion that light was homogeneous, 
had upon this principle firft difcovered the laws of re¬ 
fraction, and maintained, that the perfecting of telef¬ 
copes depended on the difcovery of a method of making 
the glafles in elliptic, parabolic, and hyperbolic, figures. 
Newton, therefore, in the year 1666, applied himfelf to 
the grinding of optic-glalfes of other figures than fphc- 
rical, not entertaining, as yet, any fufpicion of the 
heterogeneous nature of light. Not fucceeding in various 
attempts which he made to the fatisfaftion of his mind, 
he procured a glafs prifm, for the purpofe of examining 
the celebrated phenomena of colours, which had been 
lately difcovered by Grimaldi. The vivid brightnefs of 
the colours produced by this experiment, at firft afford#d 
him much pleafure; but afterwards, examining them 
philofophieally, with that accuracy and circumfpeClion 
which were natural to him, he was furprifed at perceiving 
them in an oblong form, which, according to the recei¬ 
ved rule of refractions, ought to be circular. At firft he 
thought it poflible that this irregularity might be merely 
accidental; but this was a queltion which he could not 
leave without further examination. He therefore care¬ 
fully directed his enquiries to this fubjeCt; and in the 
progrefs of them difcovered an infallible method of deci¬ 
ding the point, which produced his “New Theory of 
Light and Colours.” However, this theory alone, un¬ 
expected and furprifing as the difcovery of it was, did not 
fatisfy him, but led him particularly to enquire into the 
ufe that might be made of it in improving telefcopes, 
which was his firft defign. With this view, having now 
difcovered that light was not homogeneous, but a hete¬ 
rogeneous mixture of difrerently-refrangible rays, Ire 
computed the errors arifing from this different refrangi- 
bility; and, finding them to exceed fome hundreds of 
times thefe occafioned by the circular figure of the glafles, 
he laid afide his glafs-wcrks, and directed his attention 
to the fubjeCt of reflections. But, while he was occupied 
on thefe fpeculations, the breaking out of the plague at 
Cambridge, in 1665, obliged him fuddenly to quit his 
books and ftudies, and to retire into the country. 
During more than two years after this interruption of 
his purfuits, Newton lived in a great degree fecluded 
from converfation and books; but the activity of his 
genius would not permit him to fpend his time without 
engaging in important philofophical enquiries. On the 
contrary, it w'as in this folitude that the hint firft occur¬ 
red to him, that gave rife to the fyftern of the world which 
is the main fubjeCt of his Principia. As he was fitting 
alone in a garden, fome apples falling from a tree led 
his thoughts to the fubjeCt of gravity; and, reflecting on 
the power of that principle, he began to confider, that, 
as this power is not found fenfibly diminifhed at the re- 
moteft diftance from the centre of the earth to which we 
can rife, neither at the tops of the loftieft buildings, nor 
on the fummits of the higheft mountains, it was reafon- 
able to conclude that it was a power extending much fur¬ 
ther than was ufually thought. “ Why not as high as 
the moon ?” find he to himfelf; “ and, if fo, her motion 
mull be influenced by it; perhaps fhe is retained in her 
orbit by it. However, though the power of gravity is 
not fenfibly weakened in the little change of diftance at 
which we can place ourfelves from the centre of the earth, 
yet it is very poflible, that, as high as the moon, this 
power may differ in ftrength much from what it is here.” 
To make an eftimate what might be the degree of this 
diminution, he confidered with himfelf, that, if the moon 
be retained in her orbit by the force of gravity, no doubt 
the 
