French mathematician and government official who is best remembered for his invention of the vernier caliper, an instrument for making accurate linear measurements. Taught by his scientist-father, Claude Vernier, he developed an early interest in measuring instruments. During his adult years, however, science was for him primarily an avocation. He held various positions with the government of Spain and then became commandant of the Castle of Ornans in France and later director general of the treasury in Bourgogne. In La Construction, l'usage, et les propriétés du quadrant nouveau de mathématiques (1631; “The Construction, Uses, and Properties of a New Mathematical Quadrant”), he described his new measuring instrument. The book also contained a trigonometry table for sines and a method for deriving the angles of a triangle from known measurements of its sides.