The augmentative lever, with named curves
A balance whose arm lengthens as it descends; a flexuous line and a spiral
At the top the leaf names two curves, a wavy (flexuous or tortuous) line and a spiral, the latter drawn as a coil at the upper right. Below, balance-beam diagrams with hanging weights illustrate what Leonardo calls an 'augmentative lever': the arm a c against c b gains a degree of power at every degree the front a descends, because in descending the lever lengthens while the counter-lever shortens. A lower diagram lettered d, e, f is offered as the demonstrating figure.
On this page
The augmentative lever a c against c b
The balance or lever a c set against c b is termed augmentative because, at each degree the front a descends, it acquires a degree of power. This happens because as a descends the lever arm lengthens and the counter-lever shortens, as shown by the figure d e f below.
Flexuous line and spiral line
The page labels a wavy line as 'flexuous or tortuous' and a coiled line as a 'spiral line'. The spiral is drawn as a tight coil at the upper right, beside the wavy stroke at the top.