a "mighty rustling of silks," the elegant
crowd made its way to the auditorium for one of the famous weekly
lectures. The speaker on this occasion was James Joseph Sylvester, a
small intense man with an enormous head, sometime professor of
mathematics at the University of Virginia, in America, and more recently
at the Royal Military Academy in Woolwich. He spoke from the same
rostrum that had been occupied by Davy, Faraday, Tyndall, Maxwell, and
many other notable scientists. Professor Sylvester's subject was "Recent
Discoveries in Mechanical Conversion of Motion."[43]

[Footnote 43: Sylvester, _op. cit._ (footnote 41), pp. 179-198. It
appears from a comment in this lecture that Sylvester was responsible
for the word "linkage." According to Sylvester, a linkage consists of an
even number of links, a "link-work" of an odd number. Since the fixed
member was not considered as a link by Sylvester, this distinction
became utterly confusing when Reuleaux's work was published in 1876.
Although "link" was used by Watt in a patent specification, it is not
probable that he ever used the term "link-work"--at any rate, my search
for his use of it has been fruitless. "Link work" is used by Willis
(_op. cit._ footnote 21), but the term most likely did not originate
with him. I have not found the word "linkage" used earlier than
Sylvester.]

Remarking upon the popular appeal of most of the lectures, a
contemporary observer noted that while many listeners might prefer to
hear Professor Tyndall expound on the acoustic opacity of the
atmosphere, "those of a higher and drier turn of mind experience
ineffable delight when Professor Sylvester holds forth on the conversion
of circular into parallel motion."[44]

[Footnote 44: Bernard H. Becker, _Scientific London_, London, 1874, pp.
45, 50, 51.]

Sylvester's aim was to bring the Peaucellier linkage to the notice of
the English-speaking world, as it had been brought to his attention by
Chebyshev--during a recent visit of the Russian to England--and to give
his listeners some insight into the vastness of the field that he saw
opened by the discovery of the French soldier.[45]

[Footnote 45: Sylvester, _op. cit._ (footnote 41), p. 183; _Nature_,
November 13, 1873, vol. 9, p. 33.]

"The perfect parallel motion of Peaucellier looks so simple," he
observed, "and moves so easily that people who see it at work almost
universally express astonishment that it waited so long to be
discovered."