Vertical screw turned by a lever; a hemisphere
Red-chalk note that the upright screw's lever must be able to twist, above a wireframe hemisphere
Drawn in red chalk with the notebook turned upside down, the page pairs a mechanical study with a geometric one. At the foot of the sheet a boxed apparatus sends a long lever-arm projecting to the right: a vertical (upright) screw meant to be rotated by that lever, with the note that its lever should be able to twist. Above, a hemisphere is sketched as a wireframe of curved gridlines set over a small circle. A short line of mirror-script writing runs between the two drawings.
On this page
Vertical screw rotated by a lever
A boxed mechanism at the foot of the page carries a long horizontal arm reaching to the right. It represents a vertical, upright screw to be turned by means of that lever, and the accompanying note specifies that the lever of the upright screw should be able to twist.
Hemisphere drawn as a wireframe
At the top of the sheet a hemisphere is laid out with curved meridian and parallel lines, set over a small circle. The caption labels it simply a hemisphere.