Recto: Notes on the geometry of optics; colours of the rainbow; an eye looking through a spectrum; light falling through a glass of water; a nude man bending as if pulling a rope. Verso: Geometry of optics, illustrated by diagrams; tracing from recto of nude man; 5 sketches of a man using an axe; the inerruptions of rays of light. The sheet was originally folded twice & thus given 4 inventory no's, SA 919150,'151 &