Elements of Dynamic

Elements of Dynamic is a book published by William Kingdon Clifford in 1878. In 1887 it was supplemented by a fourth part and an appendix. The subtitle is "An introduction to motion and rest in solid and fluid bodies". It was reviewed positively, has remained a standard reference since its appearance, and is now available online as a Historical Math Monograph from Cornell University.

On page 95 Clifford deconstructed the quaternion product of William Rowan Hamilton into two separate "products" of two vectors: vector product and scalar product, anticipating the complete severance seen in Vector Analysis (1901). Elements of Dynamic was the debut of the term cross-ratio for a four-argument function frequently used in geometry.

Clifford uses the term twist to discuss (pages 126 to 131) the screw theory that had recently been introduced by Robert Stawell Ball.

A review in the Philosophical Magazine explained for prospective readers that kinematics is the "study of the theory of pure motion". Noting the nature of "progressive training" required for mathematics, the reviewer wondered "For what class of readers is the book designed?"

Richard A. Proctor noted in The Contemporary Review (33:65) that there are "few errors in the work, and even misprints are few and far between for a treatise of this kind." He did not approve of Clifford’s coining of "odd new words as squirts, sinks, twists, and whirls." Proctor quoted the last sentence of the book: "Every continuous motion of an infinite body may be built up of squirts and vortices."

In a "Sketch of Professor Clifford" in June 1879 the journal Popular Science said "It will probably not take high rank as a university text-book, for which it was intended, but is much admired by mathematicians for the elegance, freshness, and originality displayed in the treatment of mathematical problems."

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