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

1990; Elsevier BV; Volume: 32; Issue: 4 Linguagem: Inglês

10.1016/0020-7403(90)90099-5

1879-2162

W. Johnson,

Mechanics and Biomechanics Studies

After describing Robins' ballistic pendulum in general an outline is presented of the contributions to the elementary theory of the impact of translating point masses between the time of Marcus Marci (b.1595) and Christopher Wren (1632–1723). The specific work of Christian Huygens (1629–1695) especially, is described for relevant theory of the compound pendulum. A brief outline of the early lives of Robins and Cassini is given leading to an account of how the latter came to be involved, probably being the first scientist recorded as using a ballistic pendulum. The author's search for a written account of Cassini's work, in French, was located in the Procèsverbaux—the original hand-written record of scientific work as reported to the French Academy—for 1707. An abridgment of the reports was subsequently printed in the Philosophical History and Memoirs of the Academy and the latter eventually rendered into English by Ephraim Chambers (with Professor John Martyn as a co-author) in 1742. The latter may be contrasted with Benjamin Robins' own account of his pendulum design, use and experiments as given in his book, New Principles of Gunnery, published in 1742. Some reference to Euler's reception and reaction to the latter is noticed. Seemingly, Robins was not aware of Cassini's work and in any case used the pendulum to great and, different, purposes. As far as the author is aware no paper or publication, and but one book—and that minimally—in English has ever noticed or assessed the claim of Cassini to a share in the invention of the ballistic pendulum. The purpose of this paper is less to establish a priority than to put on record a truer account of the origins of the ballistic pendulum. (Ballistics: from the Greek βαλλεìv, to throw, and pertaining to the throwing of projectiles.) Several useful Notes about people, apparatus and events, are appended for improving understanding of the background of the times in which Cassini and Robins lived.