This Month in Physics History

April 15, 1452: The Birth of a Visionary — Leonardo da Vinci

In 1994, multi-billionaire Bill Gates paid a record $30 million for Leonardo da Vinci's Codex Leicester. Heralded as the epitome of the "Renaissance man," da Vinci was known chiefly for artistic masterpieces like "The Last Supper" and the "Mona Lisa" until the 20th century, when monks exhumed and restored the Codex manuscripts in the 1960s. The sketches and notations depicted therein—all rendered in da Vinci's notorious backwards handwriting, readable only with the aid of a mirror—cemented his reputation as one of the greatest scientific minds of his era.

Credit: American Museum of Natural History Library

Born April 15, 1452, da Vinci was the illegitimate son of a Florentine notary, Ser Piero d'Antonio. Raised by his father, da Vinci received the standard education of the time—reading, writing and arithmetic—and when his latent artistic talents presented themselves as he approached adolescence, he was apprenticed to the renowned workshop of Andrea del Verrochio in Florence. There he learned painting and sculpture as well as useful technical and mechanical skills, such as grinding and mixing pigments, basic perspective geometry, and working with clay and bronze. By the time he was accepted into the painter's guild in 1472, he was already making sketches of pumps, weapons, and other ingenious machines in addition to his artistic pursuits. He would seek to balance those two interests throughout his life, with varying degrees of success.

In 1482, da Vinci entered the service of Ludovico Sforza, the Duke of Milan. Ironically, he earned the position by trumpeting his engineering skills and plans for designing advanced weaponry and fortified structures, rather than his skills as an artist.

The Duke kept him busy painting, sculpting and designing elaborate court festivals, as well as armaments, but da Vinci still managed to continue his studies in geometry by reading Euclid, Battista Alberti's books on architecture, and Piero della Francesca's On Perspective in painting, becoming so engrossed in the subject that he reportedly neglected his painting.

His real achievements in this period were scientific. He devised several methods of squaring the circle, relying solely on mechanical methods, and wrote a book around 1498 on the elementary theory of mechanics. He also foresaw the possibility of constructing a telescope in his Codex Atlanticus (1490) in which he writes of "making glasses to see the moon enlarged," although the device would not be realized for another 100 years. By 1513 he had expanded the basic concept, envisioning a means of projecting the image of a single planet onto the base of a concave mirror, the reflection of which would magnify the surface of the planet.

In 1499, French armies invaded Milan and the Duke was defeated, terminating da Vinci's employment with him. Now without a wealthy patron, da Vinci traveled first to Mantua, then to Venice, finally landing in Florence, where he focused as much attention on mathematical studies as he did on painting. By 1503 the city was under siege, so he concocted a grand scheme to divert the river Arno behind Pisa. He also produced plans for a canal to allow Florence access to the river.

His observations were often accompanied by precise illustrations of the objects or phenomena under analysis, along with explanatory notes, and over his lifetime he amassed volumes of such notebooks detailing studies ranging from astronomy and the formation of fossils to the growth of plants and action of light.

Like many artists and doctors of his day, da Vinci engaged in the practice of dissecting cadavers—as quickly as possible, given the lack of refrigeration and unavailability of formaldehyde in 15th century Italy—to study human anatomy, and this certainly influenced his art. But the scientist within him was equally intrigued by the structure of limbs and their dependence on nerves and joints, as well as the function of the cervical vertebrae, small organs, and capillaries. He was also enthralled by levers and gears, which lay at the heart of many of his sketched machines, including early prototypes of the bicycle, the helicopter, cranes, an automatic turnspit, an "auto-mobile," and weaponry like catapults, missiles, multi-barreled machine guns, grenades, mortars, and even a precursor to the modern tank.

His fascination with water, then the primary source of power, resulted in his design of advanced water wheels, a steam-powered cannon, and a device to measure humidity in the atmosphere. He also conceived of floating snowshoes to enable a man to walk on water; a life preserver to remain afloat; devices to attack and sink ships from underwater; and an "unsinkable" double-hulled ship, as well as dredges for clearing harbors and canals.

In 1513, his health beginning to fail, da Vinci moved to Rome. Three years later, he entered the service of King Francis of France (a great admirer) as first painter, architect and mechanic to the King. He died on May 2, 1519, in Cloux, France, at the age of 67.

Da Vinci was a rarity in his era for his emphasis on repeated testing of direct observations—a principle which underlies the method of scientific study that dominated well into the 19th century. For example, he undertook a systemic study of the flight of birds, and tried to apply those same principles in his designs for a flying machine. As such, da Vinci bridged the gap between an unscientific, highly superstitious medieval approach to scientific questions—which frequently bore more similarity to philosophy than science—and the empiricism of later ages.