Leonardo da Vinci’s ‘irrelevant’ scribbles possibly reveal the first known record of the laws of friction


A worn-out notebook dotted with scribbles and a faint sketch of an old woman at the top, contains the following statement – cosa bella mortal passa e non dura (or “mortal beauty passes and does not last”). Dating back to 1493 AD, this page was composed by none other than the great Leonardo da Vinci himself – though his scribbles were dismissed as merely ‘irrelevant’ by a 20th century art historian. However a detailed re-analysis project conducted by Ian Hutchings, a professor at the University of Cambridge, has revealed how the notebook might be the first known source where da Vinci recorded his understanding of the laws of friction.

Now it should be noted that from the historical perspective, Leonardo da Vinci is often considered as the one of the pioneers who conducted a systematic study of friction that (possibly) was a precursor to the modern science of ‘tribology’. But the actual details of his observations and studies remained scant. However this time around, Professor Hutchings was able to identify the first known diagrams that pertain to the scope of friction, inside the aforementioned notebook that only measures 92 mm x 63 mm.

Interestingly enough, the sketch of the old woman – possibly a caricature of Helen of Troy, was the initial ambit that attracted historians in early 20th century. Unfortunately, the then-Director of the Victoria and Albert Museum dismissed the scribbles as ‘irrelevant notes and diagrams in red chalk’. But these very diagrams ‘in red chalk’ proved to be the key to understanding da Vinci’s concepts pertaining to the scope of friction.

To that end, the researchers have observed how the diagrams represent rows of blocks that are being pulled by a weight hanging over the pulley. Suffice it to say, similar diagrams are still demonstrated in standard modern-day physics books. As Professor Hutchings said –

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. These are the ‘laws of friction’ that we nowadays usually credit to a French scientist, Guillaume Amontons, working two hundred years later.

Quite intriguingly, da Vinci’s ‘affair’ with friction didn’t just stop at these diagrammatic sketches from 1493 AD. The inventor extraordinaire contrived purposeful applications (for two decades) that were dictated by the laws of friction, as is evident from his penchant for conceptualizing machine elements and various mechanisms. Simply put, the understanding of the principles of friction must have played its integral part when contriving designs of the machine components like wheels-and-axles and screw-threads and pulleys.

Unfortunately, as is often the case in matters of history, Leonardo da Vinci’s contribution to the subject was lost over time, relegated to seemingly abstruse sketches and obscure diagrams. In that regard, its influencing factor on the modern science of ‘tribology’ was rather limited, with Amontons having no prior knowledge of any such medieval ‘findings’.


Credit: V&A Museum, London

The study was published in the Science Direct journal. For more information, you can also take a gander at this pdf link (from www.ifm.eng.cam.ac.uk).

Source: Phys

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