d Evans linkages are cognates) because the
Roberts-Chebyshev theorem escaped my earlier search, as it had
apparently escaped most others until 1958. See R. S. Hartenberg and J.
Denavit, "The Fecund Four-Bar," _Transactions of the Fifth Conference on
Mechanisms_, Cleveland, Penton Publishing Company, 1958, pp. 194-206,
reprinted in _Machine Design_, April 16, 1959, vol. 31, pp. 149-152. See
also A. E. R. de Jonge, "The Correlation of Hinged Four-Bar
Straight-Line Motion Devices by Means of the Roberts Theorem and a New
Proof of the Latter," _Annals of the New York Academy of Sciences_,
March 18, 1960, vol. 84, art. 3, pp. 75-145 (published separately).]

It was during this same summer of 1876, at the Loan Exhibition of
Scientific Apparatus in the South Kensington Museum, that the work of
Franz Reuleaux, which was to have an important and lasting influence on
kinematics everywhere, was first introduced to English engineers. Some
300 beautifully constructed teaching aids, known as the Berlin kinematic
models, were loaned to the exhibition by the Royal Industrial School in
Berlin, of which Reuleaux was the director. These models were used by
Prof. Alexander B. W. Kennedy of University College, London, to help
explain Reuleaux's new and revolutionary theory of machines.[55]

[Footnote 55: Alexander B. W. Kennedy, "The Berlin Kinematic Models,"
_Engineering_, September 15, 1876, vol. 22, pp. 239-240.]

Scholars and Machines

When, in 1829, Andre-Marie Ampere (1775-1836) was called upon to prepare
a course in theoretical and experimental physics for the College de
France, he first set about determining the limits of the field of
physics. This exercise suggested to his wide-ranging intellect not only
the definition of physics but the classification of all human knowledge.
He prepared his scheme of classification, tried it out on his physics
students, found it incomplete, returned to his study, and produced
finally a two-volume work wherein the province of kinematics was first
marked out for all to see and consider.[56] Only a few lines could be
devoted to so specialized a branch as kinematics, but Ampere managed to
capture the central idea of the subject.

[Footnote 56: Andre-Marie Ampere, _Essai sur la philosophie des
sciences, une exposition analytique d'une classification naturelle de
toutes les connaissances humaines_, 2 vols., Paris, 1838 (for origin of
the project, see vol. 1, pp. v, xv).]

Cinematique (from the G