Folio 57

A red chalk study of a pointed rod, likely a component for a larger mechanical device, annotated with notes on its physical properties.

Above the vertical rod on the top left:
thin and sharp

Mechanical study in sanguine showing a timber or metal frame with internal supports. The sketch demonstrates Leonardo's method of visualizing three-dimensional structures with cross-sections and functional annotations.

Inside the mechanical frame on the left side:
dry The Italian word "secco" (dry) may refer to the seasoning of the wood or a component intended to function without lubrication.

Secondary study of a vertical component with associated mirror-written text regarding its required thickness.

To the right of the mechanical frame:
these
must not
be thin