Beams shoring earth; rack-and-pinion reversing gear
A statics rule on the line of force, with a reversing transmission
In red chalk, with the page inverted, Leonardo states a principle of statics: supporting a load grows harder as the point of contact moves away from the line of its mover. Above, he draws a rack-and-pinion transmission fitted with a device for reversing the direction of rotation, backed by a large disc. Below is a right-angled frame braced by an oblique beam, of the kind used to shore up a mass of earth.
On this page
Contact away from the line of the mover
The note argues that if the contact of a supported body with the earth beneath it does not lie along the line of its mover, the task becomes the more difficult the farther that contact is from the line of force.
Rack-and-pinion with rotation-reversal
A toothed wheel meshes with racks above and below so that turning it drives an alternating stroke; a large disc behind the gear may serve as a flywheel.
Oblique beam bracing a mass of earth
A right-angled frame stiffened by a diagonal strut sketches the vertical and oblique beams used to hold back a bank of earth.