Justin Croft Antiquarian Books - Rare and Antiquarian Books and Manuscripts

First edition. “New Principles of Gunnery transformed ballistics into a Newtonian science. Galileo's vacuum theory was the only practical theory before 1742, but only for low-velocity mortars as demonstrated in Bélidor's Le bombardier français (1731). Robins made it applicable for gunpowder weaponry in general. His key contribution was the invention and utilization of the ballistic pendulum. With Huygens's law of pendulum motion and Newton's law of linear momentum, he deduced the bullet's impact velocity from the subsequent swing angle. Robins then used the ballistic pendulum to verify his interior-ballistics theory, relying on Boyle's law, the thirty-ninth proposition from book one of the Principia, and the pneumatic chemistry techniques of Francis Hauksbee the elder and Stephen Hales. By applying Newton's second law of motion to velocity measurements at varying ranges, Robins also obtained the air-resistance force acting on musket balls. This revealed the significant limitations of Galileo's vacuum ballistics theory and of Newton's air-resistance function when approaching the speed of sound” (Steele in Oxford DNB). Robins was born of Quaker stock in Bath. He was initially self-educated but was later taught by the Newtonian editor Henry Pemberton and became a significant exponent of Newton’s physics. He had been elected a fellow of the Royal Society in 1727. His New principles of gunnery was widely-read and was translated into German by Euler and also into French.