y steam engines,
demolishing for all time the fond hopes of ingenious but ill-informed
inventors who think that improvements and advances in mechanism design
consist in contortion and complexity.

The chapter on synthesis was likewise fresh, but it consisted of a
discussion, not a system; and Reuleaux stressed the idea that I have
mentioned above in connection with Willis' book, that synthesis will be
successful in proportion to the designer's understanding and
appreciation of analysis. Reuleaux tried to put the designer on the
right track by showing him clearly "the essential simplicity of the
means with which we have to work" and by demonstrating to him "that the
many things which have to be done can be done with but few means, and
that the principles underlying them all lie clearly before us."[85]

[Footnote 85: Reuleaux, _op. cit._ (footnote 68), p. 582.]

It remained for Sir Alexander Blackie William Kennedy (1847-1928) and
Robert Henry Smith (1852-1916) to add to Reuleaux's work the elements
that would give kinematic analysis essentially its modern shape.

Kennedy, the translator of Reuleaux's book, became professor of
engineering at the University College in London in 1874, and eventually
served as president both of the Institution of Mechanical Engineers and
of the Institution of Civil Engineers. Smith, who had taught in the
Imperial University of Japan, was professor of engineering at Mason
College, now a part of Birmingham University, in England.

While Reuleaux had used instant centers almost exclusively for the
construction of centrodes (paths of successive positions of an instant
center), Professor Kennedy recognized that instant centers might be used
in velocity analysis. His book, _Mechanics of Machinery_, was published
in 1886 ("partly through pressure of work and partly through ill-health,
this book appears only now"). In it he developed the law of three
centers, now known as Kennedy's theorem. He noted that his law of three
centers "was first given, I believe, by Aronhold, although its previous
publication was unknown to me until some years after I had given it in
my lectures."[86] In fact, the law had been published by Siegfried
Heinrich Aronhold (1819-1884) in his "Outline of Kinematic Geometry,"
which appeared in 1872 alongside Reuleaux's series in the journal that
Reuleaux edited. Apparently Reuleaux did not perceive its particular
significance at that time.[87]

[Footnote 86: Alexander B. W.