Art History

The Laws of Friction Were Found in "Irrelevant" da Vinci Scribbles

In the 1920s, a museum director looked at a page in Leonardo da Vinci's notebook and deemed the bulk of its contents "irrelevant notes and diagrams in red chalk." But when a professor revisited the page in 2016, he found that these scribbles contained groundbreaking findings: the first written records demonstrating the laws of friction.

Read Between the Lines

The discovery was made and published in April 2016 by Ian Hutchings, a professor at the University of Cambridge. It's long been known that da Vinci was responsible for conducting the first study of friction, but it was unclear how and when he actually came up with it until Hutchings examined one specific page from da Vinci's 1493 notebook. It's a tiny book — roughly 3 inches by 2 inches (92 millimeters by 63 millimeters), about the size of a book of stamps — and yet it's so packed with insights that this single page of the notebook had already been subject to scrutiny back in the 1920s. In those days, people were interested in a pencil sketch of an older woman some speculated was Helen of Troy.

The pivotal friction sketches occupy the page just below the woman and were made with a different color of pencil. The drawings show rows of blocks being pulled by a weight that's hanging over a pulley. Hutchings saw what past researchers didn't: The rough geometrical figures demonstrated the laws of friction. Da Vinci clearly knew that "the force of friction acting between two sliding surfaces is proportional to the load pressing the surfaces together," Hutchings explained, "and that friction is independent of the apparent area of contact between the two surfaces." What's more, his sketches substantially predate when people believe these laws were first discovered.

Gimme Friction

Da Vinci already had a robust legacy — as the painter of the "Mona Lisa" and the titular figure in "The Da Vinci Code," among other things — but this discovery has a major impact on the field of tribology. Despite appearances, this is not the study of tribes; it's the study of friction, lubrication, and associated physics phenomena.

The discovery of the laws of friction has historically been attributed to French scientist Guillaume Amontons, who worked in the 1600s. However, da Vinci's sketches reveal that Amontons really rediscovered the laws. Da Vinci's private discovery made no impact on tribology as a field (until now) — but he was still first, officially speaking. The recently discovered notebook page wasn't his only contribution to the field, either. Da Vinci went on to study tribology for roughly 20 years; he loved to sketch complex machinery, and that meant understanding the ways friction impacted wheels, axles, screw threads, and pulleys.

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For the full story of this master artist, there's no one better than a master biographer: Walter Isaacson's "Leonardo Da Vinci" is a #1 New York Times bestseller. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Mae Rice August 17, 2016

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