Diagrams of Light Rays and the Boundary of the Luminous
Ray schemes with lettered points, geometric constructions and arithmetic calculations
The sheet is crowded with small ink diagrams of light rays and geometric figures, several accompanied by short lettered captions. One scheme marks the line a b as the boundary of the luminous, another pairs points m, n, f and g in a rule of correspondence, and a block of worked arithmetic sits among the figures. Alongside the ray studies are double-cone (hourglass) forms, pinwheel circles and a long vertical shaft or instrument drawn in metalpoint. The sheet carries further faint notes beyond the captions transcribed here.
On this page
The line a b bounds the luminous
A small labelled scheme marks the line a b as the boundary (termine) of the luminous body. It belongs to a group of ray diagrams studying how far light reaches and where its edge falls.
Correspondence of touching points (m, n, f, g)
A ray scheme labelled m n and f g states that when n touches m, f will touch g. It expresses a geometric correspondence linking the motion of one pair of points to the other.
Worked arithmetic among the diagrams
A block of figures accompanies the ray schemes, including numbers such as 14, 77, 111, 308 and 144. They read as multiplication or division worked out beside the drawings.