Ahead of His Time: Leonardo and The Codex Leicester

The Codex Leicester is a set of notes, written and illustrated by Leonardo da Vinci between 1506 and 1510, which reflect his observations and experiments on the nature and movement of water. 

While water is the Codex’s central theme, it also covers a variety of other scientific and technological subjects, including astronomy, geology, and hydraulic engineering.

A true scientist, Leonardo studied the world with intense curiosity and a keen analytical eye. 

On folio 36r, Leonardo devises an experiment with smoke and black velvet.

He used this experiment to demonstrate his correct hypothesis that the blue appearance of the air is caused by the darkness beyond it.

He used this experiment to demonstrate his correct hypothesis that the blue appearance of the air is caused by the darkness beyond it.

On the same page,
Leonardo theorizes that mountains and continents were once underwater...

... formed by underground caverns shifting and collapsing, the subsequent re-balancing of earth and water, and the re-centering of the earth’s center of gravity.

... formed by underground caverns shifting and collapsing, the subsequent re-balancing of earth and water, and the re-centering of the earth’s center of gravity.

Some aspects of Leonardo's theory about the formation of mountains are precursors to the modern scientific theory of plate tectonics.

On folio 2r, Leonardo hypothesizes that the glow of the dark part of the moon during the crescent phase is a reflection of light from the earth’s oceans.

This is the earliest known attempted explanation of the lumen cinereum, or “ashen light”, of the shaded portion of the moon. This phenomenon is now known as “earthshine”.

This is the earliest known attempted explanation of the lumen cinereum, or “ashen light”, of the shaded portion of the moon. This phenomenon is now known as “earthshine”.

Leonardo contemplates the then-prevailing theory that the heat of the sun draws water up from underground caverns to a mountain’s summit. 

On folio 3v, he rejects this theory based upon his observations of the natural world: mountain springs are not more active in the summer, when the sun is warmer.

He devises a distillation experiment which demonstrates that in an open system heat from above will pull air in instead of drawing water upward.

Leonardo refutes the biblical account of the Deluge as the reason that seashells and marine fossils are found on high mountains.

On folio 10v, he hypothesizes that the Mediterranean Sea once covered much of Europe and North Africa.

He writes, “In Italy, where today birds fly in flocks, fishes used to move in great shoals”.

In folio 14v, Leonardo explores the dynamic effect of objects dropped in water:

spherical objects...

spherical objects...

and angular objects.

Leonardo’s closely observed drawing of a drop water foreshadows modern high-speed stroboscopic photography, which can capture images of objects moving too quickly for the eye to see.

Leonardo’s closely observed drawing foreshadows modern high-speed stroboscopic photography, which can capture images of objects moving too quickly for the eye to see.