The origin of the ballistic pendulum: The claims of Jacques Cassini (1677-1756) and Benjamin Robins (1707-1751) (Q757328)

The paper discusses the historical origins of ballistic pendulum in the first half of the eighteenth century and shows that the credit for its invention should not only go to the Englishman Robins but also to the French born Italian Cassini. The details of the construction of the ballistic pendulum by Robins are given with ample illustrations. The author shows how Robins was led to this invention by his understanding of the principle of conservation of momentum and his aim of measuring accurately the initial velocity of a bullet. The same search led him to measure the resistance offered by the air. The paper makes it clear why engineers should know the theoretical as well as the historical roots of engineering devices - an aspect which is often neglected in engineering education.