Red-chalk mechanism with lettered parts and a scaled diagram
A drum-and-crank device labelled a, b, n, above a rectangle crossed by a diagonal
In red chalk Leonardo draws a mechanism built around a large drum or wheel set in a frame with cranks and cords, its parts keyed with the letters a, b and n. Two accompanying notes tell him to make the element a b shorter and to try the space a n larger or smaller. Below, a rectangle is crossed by a diagonal and ruled with tick marks along its edges, a scaled geometrical construction. Faint mirror-script is present on the sheet that the bundle does not transcribe.
On this page
Element a b to be made shorter
The central drawing is keyed with the letters a and b, with the instruction that a b should be shorter. The note adjusts the length of that member of the mechanism.
Trying the space a n larger or smaller
A lower drawing carries the letters a and n, with the reminder to try making the space a n larger or smaller. Leonardo tests how varying that gap affects the device.
Rectangle crossed by a diagonal and scaled
At the foot of the sheet a rectangle is divided by a diagonal and ruled with regular tick marks along its top and side. A curved line rises within it, giving a scaled geometrical construction.