A beam rotating through a quarter-circle
A faint red-chalk diagram marking the descending series 12, 6, 3, 1 1/2 around a quadrant
Drawn with the notebook inverted and now very faint in red chalk, the page shows a bar or beam swinging through a quarter-circle. Radiating lines within the quadrant are marked with the descending series 12, 6, 3, 1 1/2, each roughly half the one before. A ruled rectangular grid is sketched above the quadrant.
On this page
Beam rotating through a quarter-circle
A bar pivots at one corner and sweeps through a quadrant, its successive positions ruled as radiating lines. The steps are numbered 12, 6, 3, 1 1/2, a halving sequence suggesting how a turning effect changes with position.
Quadrant with ruled subdivisions
The motion is set inside a quarter-circle whose span is divided by straight lines, with a rectangular grid drawn above it. The numbers 12, 6, 3, 1 1/2 label the divisions of the quadrant.