London

There were two great divides in Newton’s adult life: in the middle 1660s from
the rural surroundings of Lincolnshire to the academic world of Cambridge, and
thirty years later, when he was fifty-four, from the seclusion of Cambridge to the
social and political existence of a well-placed civil servant in London. The move
to London was probably inspired by a feeling that his rapidly growing fame
deserved a more material reward than anything offered by the Lucasian Professorship.
We can also surmise that he was guided by an awareness that his formidable
talent for creative work in science was fading.
In March 1696, Newton left Cambridge, took up residence in London, and
started a new career as warden of the Mint. The post was offered by Charles
Montague, a former student and intimate friend who had recently become chancellor
of the exchequer. Montague described the warden’s office to Newton as asinecure, noting that “it has not too much bus’nesse to require more attendance
than you may spare.” But that was not what Newton had in mind; it was not in
his character to perform any task, large or small, superficially.
Newton did what he always did when confronted with a complicated problem:
he studied it. He bought books on economics, commerce, and finance, asked
searching questions, and wrote volumes of notes. It was fortunate for England
that he did. The master of the Mint, under whom the warden served, was Thomas
Neale, a speculator with more interest in improving his own fortune than in
coping with a monumental assignment then facing the Mint. The English currency,
and with it the Treasury, were in crisis. Two kinds of coins were in circulation,
those produced by hammering a metal blank against a die, and those
made by special machinery that gave each coin a milled edge. The hammered
coins were easily counterfeited and clipped, and thus worth less than milled
coins of the same denomination. Naturally, the hammered coins were used and
the milled coins hoarded.
An escape from this threatening problem, general recoinage, had already been
mandated before Newton’s arrival at the Mint. He quickly took up the challenge
of the recoinage, although it was not one of his direct responsibilities as warden.
As Westfall comments, “[Newton] was a born administrator, and the Mint felt the
benefit of his presence.” By the end of 1696, less than a year after Newton went
to the Mint, the crisis was under control. Montague did not hesitate to say later
that, without Newton, the recoinage would have been impossible. In 1699 Neale
died, and Newton, who was by then master in fact if not in name, succeeded
him.
Newton’s personality held many puzzles. One of the deepest was his attitude
toward women. Apparently he never had a cordial relationship with his mother.
Aside from a woman with whom he had a youthful infatuation and to whom he
may have made a proposal of marriage, there was one other woman in Newton’s
life. She was Catherine Barton, the daughter of Newton’s half-sister Hannah
Smith. Her father, the Reverend Robert Barton, died in 1693, and sometime in
the late 1690s she went to live with Newton in London. She was charming and
beautiful and had many admirers, including Newton’s patron, Charles Montague.
She became Montague’s mistress, no doubt with Newton’s approval. The affair
endured; when he died, Montague left her a generous income. She was also a
friend of Jonathan Swift’s, and he mentioned her frequently in his collection of
letters, called Journal to Stella. Voltaire gossiped: “I thought . . . that Newton
made his fortune by his merit. . . . No such thing. Isaac Newton had a very charming
niece . . . who made a conquest of Minister Halifax [Montague]. Fluxions and
gravitation would have been of no use without a pretty niece.” After Montague’s
death, Barton married John Conduitt, a wealthy man who had made his fortune
in service to the British army. The marriage placed him conveniently (and he
was aptly named) for another career: he became an early Newton biographer.
Newton the administrator was a vital influence in the rescue of two institutions
from the brink of disaster. In 1703, long after the recoinage crisis at the
Mint, he was elected to the presidency of the Royal Society. Like the Mint when
Newton arrived, the society was desperately in need of energetic leadership.
Since the early 1690s its presidents had been aristocrats who were little more
than figureheads. Newton quickly changed that image. He introduced the practice
of demonstrations at the meetings in the major fields of science (mathematics,
mechanics, astronomy and optics, biology, botany, and chemistry), found thesociety a new home, and installed Halley as secretary, followed by other disciples.
He restored the authority of the society, but he also used that authority to
get his way in two infamous disputes.
On April 16, 1705, Queen Anne knighted Newton at Trinity College, Cambridge.
The ceremony appears to have been politically inspired by Montague
(Newton was then standing for Parliament), rather than being a recognition of
Newton’s scientific achievements. Political or not, the honor was the climactic
point for Newton during his London years.