Leonardo da Vinci is undisputed as a painter and inventor, from the Mona Lisa to his flying machines. What is less well known is that he also made numerous contributions to science and, in a consistently eclectic manner, touched on the physics, geology, and botany of his time. These contributions demonstrate how the Tuscan artist was able to access advanced knowledge despite being excluded from traditional channels for the dissemination of knowledge, particularly the university.

Considered by the philosopher Pierre Duhem in 1900 as the missing link between medieval science and modern science , Leonardo da Vinci has since sometimes been judged incapable of having had access to scientific knowledge and of having been a poor scholar . Indeed, his illegitimate birth prevented him from attending university (which was forbidden to illegitimate children). Some experts even tried to confine him to the role of a technician and went so far as to criticize the machines he designed by emphasizing that they were simple repetitions of those of predecessors or by describing them as impossible.

Today, however, a careful examination of the Tuscan’s writings proves that, on the contrary, he had found ways to gain access to the culture that was denied him and, even better, had been able to challenge scholastic knowledge through experience – by finding scholars who could explain to him what he did not have direct access to, for example the mathematician Luca Piacioli to gain access to Euclid, or the physician from Pavia Marcantonio della Torres to understand the ideas of Galen.

In the field of technology, he was certainly inspired by medieval engineers such as the architect Filippo Brunelleschi or the engineers Le Taccola and Francesco di Giorgio, but he went beyond them by inventing a method of reducing mechanics to the art (which consists of having an analytical approach to mechanics by identifying on paper all the simple elements, such as gears, cams, escapements, springs, in order to be able to compose combinations arranging these machine elements), by perfecting technical drawing and by drawing inspiration from living things for flying machines.

Thus, he was responsible for major breakthroughs in the many fields in which he excelled – even though his texts remained in manuscript form until 1883, which prevented him from passing on his discoveries.

From observing the world to the concepts of physics

If we start with physics, someone who had not been trained in Aristotelianism or the theories of Archimedes was nevertheless able, late in life, to have the principles of ancient science explained to him (such as the four powers of nature: movement, weight, force and percussion) and to read the basic treatises in Latin.

Thus, he was perfectly aware of the theory of antiperistasis and the medieval theory of impetus . The former stated that a thrown body continues to move forward because the air in front of it is propelled behind it and provides the thrust. Leonardo rejected this idea by accepting the concept of impetus: what pushes the body is a quality of impulse conferred on the projectile. Leonardo demonstrated this with an experiment in which he fired an arquebus into a flask (if antiperistasis worked, the water in the flask would prevent the bullet from continuing its trajectory, which is not the case).

Regarding another concept of physics, that of friction, Leonardo again proves by studying the facts that this is proportional not to the surface area of ​​contact but to the weight of the object.

Leonardo, passionate about vortices, also explored the field of hydraulics and aerodynamics, we owe to him the intuition of turbulence, surface vortices and deep vortices, induced vortices, etc.

In the field of optics, Leonardo was inspired by the 11th-century mathematician, physicist, and physician ^Alhazen  , whose real name was Ibn al-Haytham, who developed a modern theory of optics, including physiological reflections on the eye, and the introduction of mathematics into the physical sciences. Thanks to the translation of Erasmus Vitello – Vitellion in French, a 14th-century Silesian monk ^,  commentator on Alhazen and author of a treatise on perspective – he studied the eye and the light rays that he considered emitted by the object to create simulacra in the retina.

He even built a “black box” (or camera obscura , a sort of primitive camera) to simulate this phenomenon.

An excellent cartographer, Leonardo was also a remarkable geologist who theorized the role of water in erosion, understood the stacking of geological layers and explained the origin of fossils.

Raised in the countryside, he was also interested in botany, drawing all sorts of plants but also researching the rules of their growth. The painting of the Virgin of the Rocks constitutes a veritable virtual herbarium.

Anatomy, far beyond the “Vitruvian Man”

The field of anatomy is undoubtedly where the master went the furthest. Based on extensive reading, he perfected dissection methods by collaborating with physicians from Florence, Pavia (such as the Galenist Marcantonio Della Torre), and Rome, producing drawings of the body and its parts of astonishing precision.

Better still, he discovered through experiments the principle of the circulation of blood in vortices in the aortic valves, proposed interpretations of the functioning of the urogenital system, the respiratory system or the digestive system and studied the relationships between the fetus and the womb.

To understand the anatomy of the brain, and the link between the senses and memory, he poured wax into brain cavities and cut out skulls.

Leonardo and mathematics

It was perhaps in mathematics that Leonardo was weakest, despite his collaboration with the Franciscan Luca Pacioli, for whom he designed the polyhedra of the Divina Proportione . Nevertheless, mathematics continued to inspire him and he was convinced that nature is animated by geometric and arithmetic rules.

Leonardo’s scientific approach led him to produce a number of treatises which are now lost but to which he often refers, such as a treatise on water, a treatise on the flight of birds or a treatise on the elements of machines.

Bathe in the inspirations of the engineers of his time

Although Leonardo’s contributions to science have been little remembered, his work as an engineer and inventor constitutes a key element of his legend.

Here again, the Tuscan’s activity demonstrates an all-round curiosity in the mechanical arts: cranes and construction machinery, locks and hydraulic machines, textile machines, foundry machines, pumps, war machines, theatre machines, automatons, flying machines…

The chemist Marcelin Berthelot, at the beginning of the 20th ^century  , was the first to notice that many of Leonardo’s machines were inspired by the Middle Ages. The principle of the tank, for example, was already present in the Bellifortis , by Konrad Kyeser (1366-1406), and many of the siege engines proposed by Leonardo da Vinci to Ludovico Sforza, in a letter of motivation, were described by Roberto Valturio in 1472 in the De arte militari .

The principle of the parachute was also explained in a Sienese manuscript from the first half of the 15th ^century  .

In an era when intellectual property was not truly stable, engineers often adopted the ideas of their predecessors or contemporaries. Thus, a hydraulic power saw by Sienese engineers borrowed the technical uses of medieval monks, and Francesco di Giorgio borrowed Brunelleschi’s ideas for paddle-wheel ships.

Thus, Leonardo’s notebooks are filled with sketches of lifting gear or paddle steamers by Brunelleschi, mills and gears by Francesco di Giorgio Martini, or clockwork mechanisms by Della Volpaia. It is not always easy to attribute the invention of a machine designed by Leonardo to the latter because he copied his surroundings—something he readily conceded, for example when he said that an anti-friction device for bells was suggested to him by a German locksmith named Giulio Tedesco.

Some hypercritical researchers have concluded that Leonardo never built a single machine. This is jumping the gun, as some machines are attested to by several witnesses – the ambassadors of Ferrara or Venice, or even Florentine contemporaries: an automaton lion, for example, a water meter, self-supporting bridges, theatre mechanisms, etc.

Moreover, when Leonardo advises his apprentices to be wary of spies who might see his tests of flying machines from the drum of Milan Cathedral, or when he accuses German mechanics of having copied his designs for incendiary mirrors in Rome, it is clear that he is talking about concrete artifacts.

However, not all the project diagrams were necessarily implemented; this is evident when one tries to reconstruct them… and they do not work (for example, the gears of an assault tank which would make the rear and front wheels of the vehicle go in opposite directions).

Moreover, incredibly sophisticated textile machines (spinning machines, weaving looms, gold leaf beaters, beret clippers) have material strength problems that make their survival unlikely.

Leonardo’s effective contributions to 15th-century technologies

Leonardo da Vinci’s contribution to technology is first and foremost a methodological approach. For example, in his Treatise on the Elements of Machines , the Tuscan focused on reducing mechanics to simple elements (levers, cranks, screws, cams, springs, escapements, gears, etc.) in order to be able to mathematize their effects and develop combinations. Everything is then a question of timing, for example for automatic spinning machines, weaving looms, gold beaters, file cutting machines or mirror polishers. Speed ​​and power work in inverse proportion and the researcher marvels at the virtues of screws and gears.

His other contribution is a new development of technical drawing combining top view, profile view, axonometrics and exploded views.

Finally, Leonardo astonishes with his investigation of new areas, such as flight, using the observation of nature to find mechanical solutions to new problems.

The limitations of Leonardo’s work are obvious – in mathematics, for example – but contrary to what critics say, who point out the deficiencies in his training, they often lead him to go beyond tradition.

Author Bio: Pascal Brioist is a University Professor. Specialist in Leonardo da Vinci, Renaissance science and technology, and 16th and 17th century England at the University of Tours