e was driven by a steam engine. Photograph by
Science Museum, London.]

Before dismissing with a smile the quaint ideas of our Victorian
forbears, however, it is well to ask, 88 years later, whether some
rather elaborate work reported recently on the synthesis of
straight-line mechanisms is more to the point, when the principal
objective appears to be the moving of an indicator on a "pleasing,
expanded" (i.e., squashed flat) radio dial.[49]

[Footnote 49: _Machine Design_, December 1954, vol. 26, p. 210.]

But Professor Sylvester was more interested, really, in the mathematical
possibilities of the Peaucellier linkage, as no doubt our modern
investigators are. Through a compounding of Peaucellier mechanisms, he
had already devised square-root and cube-root extractors, an angle
trisector, and a quadratic-binomial root extractor, and he could see no
limits to the computing abilities of linkages as yet undiscovered.[50]

[Footnote 50: Sylvester, _op. cit._ (footnote 41), p. 191.]

Sylvester recalled fondly, in a footnote to his lecture, his experience
with a little mechanical model of the Peaucellier linkage at an earlier
dinner meeting of the Philosophical Club of the Royal Society. The
Peaucellier model had been greeted by the members with lively
expressions of admiration "when it was brought in with the dessert, to
be seen by them after dinner, as is the laudable custom among members of
that eminent body in making known to each other the latest scientific
novelties." And Sylvester would never forget the reaction of his
brilliant friend Sir William Thomson (later Lord Kelvin) upon being
handed the same model in the Athenaeum Club. After Sir William had
operated it for a time, Sylvester reached for the model, but he was
rebuffed by the exclamation "No! I have not had nearly enough of it--it
is the most beautiful thing I have ever seen in my life."[51]

[Footnote 51: _Ibid._, p. 183.]

The aftermath of Professor Sylvester's performance at the Royal
Institution was considerable excitement amongst a limited company of
interested mathematicians. Many alternatives to the Peaucellier
straight-line linkage were suggested by several writers of papers for
learned journals.[52]

[Footnote 52: For a summary of developments and references, see Kempe,
_op. cit._ (footnote 21), pp. 49-51. Two of Hart's six-link exact
straight-line linkages referred to by Kempe are illustrated in Henry M.
Cundy and A. P. Rollett, _Mathematical