Geometric Calculation for a Sundial

The image features two distinct geometric schematics on a paper surface. The upper portion displays a fan-like array of radial lines emanating from a central point 'F' toward a curved, graduated arc, with a vertical line extending downward to a horizontal base 'HK'. Below this, a secondary drawing depicts a rectangular frame with labeled scales, including Roman numerals I and II and Arabic numerals ranging from 1 to 90, likely representing hours or degrees of arc for timekeeping. The lines are rendered in sharp black ink, exhibiting the characteristic precision of seventeenth-century mathematical engraving.

This diagram belongs to the early modern tradition of gnomonics, the art of designing sundials, which was essential for both practical timekeeping and natural philosophical studies of the cosmos. It reflects the era's focus on applied geometry and the translation of celestial movement into terrestrial measurements, common in scientific treatises of the period.