He’s been dead for nearly 500 years, yet Leonardo da Vinci continues to amaze us. Scientists looking at da Vinci drawings that were once considered to be insignificant doodles and scribbles in margins of a notebook were shocked to discover that they are actually da Vinci’s explanation of the laws of friction – 200 years before they were “officially” discovered.
The sketches and text show Leonardo understood the fundamentals of friction in 1493. He knew that the force of friction acting between two sliding surfaces is proportional to the load pressing the surfaces together and that friction is independent of the apparent area of contact between the two surfaces.
Ian Hutchings, a professor of engineering at Cambridge, was the first to realize the margin drawings in a tiny notebook of da Vinci’s were explanations of friction and most likely document actual experiments da Vinci conducted. One showed rows of blocks being pulled by a weight hanging over a pulley, which illustrates one of the three laws of dry friction attributed 200 yeas later to French scientific instrument inventor and physicist Guillaume Amontons.
Why didn’t anyone analyze these doodles before Professor Hutchings? It appears that art historians studying the small notebook were distracted by the nearby drawing of an old woman in black pencil with the caption "cosa bella mortal passa e non dura," which means "mortal beauty passes and does not last." That may be true, but they should have known that da Vinci also drew pictures of things that last forever, like laws of physics.
The sketch and the notes are done in "mirror writing" from right to left – a technique da Vinci sometimes used to hide important ideas. This may have also caused those reading the notebook to ignore the drawings.
Hutchings points out in his study published in the scientific journal Wear that da Vinci was enamored by the way physical objects moved and how they moved against each other.
He appreciated that friction depends on the nature of surfaces and the state of lubrication and his use and understanding of the ratios between frictional force and weight was much more nuanced than many have suggested.
Perhaps the notebooks should have been examined by Mad magazine fans – they always look for doodles in the margins.
Wouldn't Da Vinci Doodles be a great name for a snack?