Magnificent Man’s Flying Machines

Leonardo da Vinci is justly celebrated as an artist, but his scientific inventions did not work

James Hannam

When Leonardo da Vinci died on  May 2, 1519, he left behind about 20 paintings, one large mural of The Last Supper in Milan which was already decaying, and 10,000 pages of manuscript notes. An exhibition at the National Gallery which opens on November 9 will remind us that da Vinci was terribly good at painting and drawing. But as an inventor and man of science, he achieved little. Giorgio Vasari, the biographer of the Italian artists of the Renaissance, even thought his life represented a colossal waste of a sublime talent.

Da Vinci’s celebrated anatomical sketches were an adjunct to his artistic studies. It is the quality of his drawing, rather than any physiological discoveries, that brought him fame. His near-contemporary, Andreas Vesalius, whose On the Fabric of the Human Body was published in 1543, was fully aware of the importance of good illustrations which is why he employed the studio of Titian to produce the woodcuts for his book. Da Vinci himself is alleged to have been persecuted by the Church for the crime of dissecting human bodies. But the only evidence for this is a letter in which he complains that a disgruntled employee is making trouble for him both at the hospital which provides his corpses and (rather implausibly) in front of the Pope. In fact, human dissections had been going on for 200 years in Italy as part of medical training. The Church had raised no objections. If da Vinci had to be cautious about his work on anatomy, it was because he was an amateur. He would struggle today if he was cutting up bodies without permission. 

As an inventor, da Vinci is credited with designing a parachute, a diving suit, a glider and a helicopter, among other things. In recent years, television companies have sponsored the creation of full-size versions of these machines. His design for a rigid parachute functions but has no practical utility whatsoever, while his helicopter is a non-starter. The diving suit works, but since he had no conception of keeping the air that divers breathe under pressure, it is only practical in very shallow water. His glider is the most interesting case. Full-size prototypes can stay airborne but lack stability. They spin out of control at the slightest breeze. On a television show aired in 2005, the presenters used their knowledge of modern aerodynamics to add a tail to the unwieldy glider, hugely improving its handling. Da Vinci, they assured us, would have thought of this. In any case, gliders had already been built during the Middle Ages. It was just you had to be extremely foolhardy to try one out. During the 11th century, an English monk called Eilmer of Malmesbury flew more than 200 yards after jumping off a tower. Flying, he quickly found, was only half the problem. The monk broke his legs on landing and was left lame for life. 

None of his failures as an inventor were da Vinci’s fault. After all, the poor man was writing in the 15th century without the benefit of a TV producer’s hindsight. But neither was he an especially original thinker. Books of marvellous devices date back to ancient Alexandria and were popular in the late Middle Ages. A manuscript by Villard de Honnecourt preserved in the Bibliothèque Nationale de France dates from about 1250, two centuries before da Vinci was born. It contains designs for siege engines, buildings and industrial equipment. So, as an inventor, da Vinci was merely continuing a tradition that dated back centuries. His eminence today is based on a combination of general ignorance about this tradition and the magnificent draftsmanship with which his doodles are executed.

What of da Vinci as a philosopher of nature? Perhaps the verdict of his contemporaries should count for something. Their reaction to his voluminous writings on science was simply to ignore them, although da Vinci’s habit of using mirror-writing didn’t help. His manuscripts were rapidly dispersed as collectors sought out the drawings they contained, while disregarding the words. Then, from the late 19th century and especially following the da Vinci-mania launched by the theft of the Mona Lisa in 1911, his philosophy was reassessed. 

Initially, this new look at da Vinci’s scientific notebooks caused some excitement. He rapidly gained a reputation as the ultimate Renaissance man, ahead of his time and struggling against the orthodoxies of his day. But this assessment was the result of a lack of awareness about the achievements of medieval science and astronomy. 

For instance, da Vinci’s scientific method consisted of careful observation followed by rational analysis that should lead to necessary laws. This is exactly what basic textbooks in Aristotle’s logic had taught generations of medieval students at the great universities of Paris, Oxford and Padua. Da Vinci did occasionally talk about the importance of controlled experiments. But he did not practise what he preached. For example, he agreed with Aristotle that heavy objects must fall faster than light ones. Proving that this is false requires only a very simple experiment: drop a brick and pebble from head-height. Da Vinci seems never to have bothered performing it. His notebooks also discuss impetus and motion in a way that seems to anticipate Galileo and Newton. However, historians now know that Galileo inherited many of his ideas from medieval natural philosophers such as John Buridan, who was active in the 1340s. Da Vinci’s work turns out to be mainstream and derivative.

At one point in his notebooks da Vinci wrote in large letters, apparently at random, “the sun does not move”. But elsewhere, he accepts the view that the sun, moon and other planets orbit the earth. A century earlier, Nicholas of Cusa had proposed in his bestselling On Learned Ignorance that the earth moves in a circle. He had even explained why we cannot feel this motion. Repeating an argument developed by John Buridan, Nicholas compared the earth to a ship. Without a fixed reference point, he said, when we are on a ship on a smooth sea observing another ship, we cannot tell which of them is actually moving. Likewise, when we observe the stars moving across the sky, we cannot tell whether it is the stars or the earth moving. This argument, later used by Copernicus and Galileo, does not appear in da Vinci’s work. As for Nicholas of Cusa, the Pope made him a cardinal. 

Da Vinci did have some impressive scientific insights, especially on the subjects of fluids and geology, but these never saw the light of day, primarily because he  was never able to carry any project to completion. So, comparing da Vinci’s art to his science, it is hard to disagree with Vasari. Perhaps this most celebrated son of the little Tuscan town of Vinci should have spent more time exercising his sublime talent as a painter.

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