Book Collection
"Principes d'Astronomie Sphérique, ou Traité Complet de Trigonométrie Sphérique" by Antoine Rene´ Mauduit 1765
This is a French language textbook of spherical astronomy and trigonometry. Up until the mid 19th century astronomers were only concerned with the positions and motions of heavenly bodies and spherical trigonometry is what astronomers use to compute the positions of stars on the celestial sphere from their measurements.