Moyen approché de déterminer l'ombre d'une sphère (2)

Diagrams and methods for calculating the shadow of a sphere. Two leaves, each 8.25 x 6.25 inches, in acid-free mat and archival sleeves, 12 x 9 inches. Matted with drawing-sides visible, but loosely mounted so the text on the versos can be easily examined. Very Good condition with minor soil. From a mid-19th century French student manuscript on architectural and mechanical drafting containing notes for computational and perspective drawing, studies on light and shade, reflection, etc.