Isaac Newton knew all about falling apples, but he proved less than expert when it came to playing the stock market. After the South Sea Company promised massive returns from its slave-trading enterprise, Newton gradually built up his stock. In 1720, when the price began climbing steeply, he sensibly sold—but soon made the beginner’s mistake of buying in again at a higher price, only to watch the share value suddenly plummet. By then, he had been in charge of the Royal Mint for over 20 years, so he probably kept quiet about losing a small fortune.
According to mythologised versions of this national hero, Newton was a scientific genius who soared above mundane matters. But even while he was a Cambridge professor, he had twice served as an MP, and gratefully accepted when the Chancellor of the Exchequer offered him a job as Warden of the Mint. This government appointment commanded more wealth, prestige and influence than any of his scholarly activities, and on his 55th birthday—Christmas Day 1699—Newton became its Master, a still more lucrative position that gave him a cut from the organisation’s profits.
Newton continued to confirm and refine his theories of the natural world, but he also became an elite member of metropolitan society who contributed to Britain’s ambitions for global domination. Responsible for manufacturing the country’s coins, Newton also monitored the national economy in a role comparable to governing the Bank of England today. Remaining in power until he died, Newton took decisions that affected Britain’s international trade, reputation and imperial expansion.
Confronted with a multitude of non-decimal and mutually incompatible currencies, Newton adopted the same mathematical thoroughness that had helped him to impose order on the universe. Scrawling over sheet after sheet of paper, he drew up tables, copied out memoranda and added up columns of figures. This brief, convoluted extract from one eight-page hand-written note is a typical example:
“…there has been coyned in Gold 2059384. 06. 07. If an eighth part thereof be subducted as weighty guineas culled out…& to the remainder be added the French & Spanish Pistols & Guineas which came hither from abroad {w}hen Guineas were at 30s a piece & afterwards at 22s… I’le reccon at about a million & an half.”
The guineas he refers to were recently invented coins made with gold from the African region of Guinea, one corner of the global triangular trade in enslaved people. Worth £1.05, they featured in legal documents well into the 20th century, but in Newton’s time their value fluctuated alarmingly.
Coins were conceptually different from now: instead of being tokens with minimal intrinsic value, they were composed of precious metals. In principle, a coin labelled “pound” was worth a pound after being melted down and converted into bullion, but criminals could make a quick profit by filing slivers from its rim, which made the coin smaller and therefore less valuable. The currency was literally shrinking, and Newton’s first task was to sort the situation out. Making his life still more complicated, international values were based on silver, but the value of gold was soaring. The doyen of gravity predicted confidently that it would fall of its own accord—but he was wrong. Thanks to the policies he implemented, in 1717 Britain became the first country in the world to adopt gold as its standard.
A ruthless manager, Newton weeded out internal corruption and implemented efficiency measures: he was patriotically determined to defend the nation’s coins, and his own income was tied to the Mint’s productivity. Under his strict regime, staff operated the screw-presses at a machine-like rate of almost once a second, and the Mint’s profits rose—along with his own unpopularity. Forgery was a capital offence, and Newton pursued counterfeiters savagely, even paying employees to disguise themselves and penetrate criminal rings.
Some abuse was straightforward: one Newgate prisoner swore that the new Warden was “a Rogue and if ever King James came again he would shoot him… God dam my blood so will I.” Other accusations were more subtle, such as this anonymous verse insisting that nobody—not even Newton—is immune from the gravitational attraction of personal greed:
The Principles by which Men move,
Are private interest, base Self-Love;
So far their Love or hate extends
As serves their own contracted Ends.
Newton operated not only as an administrator, but also as a practitioner. Like goldsmiths and other skilled craft workers, he belonged to an extended experimental community stretching across London. The processes of refining and testing precious metals involved the same chemical procedures and knowledge as isolating a new element or searching for the philosopher’s stone. When four men applied to become Assay Master, Newton appointed himself to supervise “a Comparative Trial before the officers they made each of them Eight Assays of Gold in four successive Fires, two in artifice, and as many of silver…” And when the Mint was accused of producing sub-standard coins, Newton personally carried out tests showing the assayers had made a mistake—at least, that’s what he claimed.
Many scientists regard Newton’s London years as an unfitting epilogue for the career of an intellectual giant, but economists see matters differently. More interested in falling stock markets than in falling apples, they are untrammelled by assumptions that the life scientific is the only one worth living. Once Newton had tasted fame and the possibilities of wealth, he wanted more of both. And that entailed moving to the capital, where he dedicated his great intellect to earning a fortune and playing an influential role in Enlightenment society.
This article is based on Patricia Fara’s latest book, Life after Gravity: Isaac Newton’s London Career (OUP)
