“ He entered the French royal artillery in 1732 as a volunteer, and became an officer in 1735. For nearly twenty years regimental duty and scientific work occupied him, and in 1752 he became captain of a company of miners. A few years later he was employed in a military mission in Prussia. In 1757, being then a lieutenant-colonel, he was lent to the Austrian army on the outbreak of the Seven Years’ War, and served as a general officer of artillery. ”