Friday (Isaac) Newton Blogging: A tree of knowledge?
Late in life Isaac Newton told a story about something that happened during the plague year of 1666.
To avoid the epidemic in the dangerous urban setting of Cambridge (population, at most, 5,000) Newton retreated to Lincolnshire, and his family’s farm, Woolsthorpe Manor.
One day that summer, (or so he said, half a century later), Newton went out the front door of his house into the garden and paused, sitting, he recalled “in a contemplative mood.” He looked at an apple tree he remembered from childhood, heavy with fruit. Perhaps his mind was idle for a moment — but then, Newton claimed, he wondered, “Why should that apple always descend perpendicularly to the ground, thought he to himself. Why should it not go sideways or upwards but constantly to the earth’s center.”
Hence Newton’s theory of gravity. Or not. Most Newton scholars have great doubt — to put it kindly — that the apple ever fell, or that if it did, anything significant occurred to young Isaac. It is suspicious that he never mentioned anything about a falling apple for decades. It is even more so given that in the intervening years, priority disputes over the essential ideas that underpinned Newton’s conception of gravity made it very useful to find some prehistoric roots to what Newton finally published.
But there is this truth: the, or rather, an apple tree actually exists. I took this photograph in January 2007, standing right in front of the Woolsthorpe main house pictured above:
What you see is a sprout from a downed trunk — which fits, more or less, as it is known that what local folklore claimed was Newton’s tree blew down in a storm in 1819. The curators of the Woolsthorpe Manor site will tell you that this is what remains of the original. Maybe so.
Some detective work in the early 50s turned up another line of Newtonian fruit descent: after Newton’s death, cuttings from the tree were grafted first onto trees at a local landowner’s estate, and later to trees at the Royal Botanical Gardens at Kew. We therefore know what breed of apple supposedly carried all that weight in Newton’s thinking: it was a Flower of Kent, a cooking apple popular in the 17th century.
One of Newtonian grafts made its way to my professional home, the little garden outside Building 11 on the MIT campus. Last fall, it fruited for the first time in the twenty or so years since the sapling was planted. It produced exactly one apple.
It was soon stolen.
You can, with some effort, buy your own bit of Newtonian legend. A nursery on the Isle of Wight sells plant that assert themselves to be descendents of the Woolsthorpe tree– though they do not ship to the US.
[Update: The material in this post was gathered in the course of researching a book about Newton’s little known career as a cop, pursuing those who would suborn the King’s currency. That book is now out, under the title Newton and the Counterfeiter. If you want to know more the intersection of the scientific revolution with the mean streets of seventeenth century London, then you can pick the book up at the usual suspects: Amazon, Powells, Barnes and Noble,Indiebound and across the pond at Amazon.co.uk, Waterstones, Blackwells, Borders,John Smith & Son.]
Image: “Isaac Newton” Sir Godfrey Kneller, 1702, Wikipedia Commons