Another of three drafts of a paper (see item C 67) to solve the famous problem of drawing in a hemispherical dome four apposing windows, so that, when these were removed, the remaining surface of the dome could be exactly measured.

Glued to the last page is a small table of azimuths or elevations along the sea route from Leith to Dover and beyond, and a jotting of several partial book titles (by Byle, James Gregory, Apian, Snell, Kepler, and one other), and item C 101, for whose entry see below.