In the 1920s, a museum director looked at a page in Leonardo da Vinci's notebook and deemed its contents "irrelevant notes and diagrams in red chalk." But when revisited in 2016, a professor found that these scribbles actually contained groundbreaking findings: the first written records demonstrating the laws of friction. 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. Hutchings examined one specific page from da Vinci's 1493 notebook and interpreted the rough geometrical figures drawn on it as a demonstration of the laws of friction. The drawings showed rows of blocks being pulled by a weight that was hanging over a pulley. Watch the video below for more on this unexpected finding.