peared shortly after 1800.
The origin of the grasshopper beam motion is somewhat obscure, although
it came to be associated with the name of Oliver Evans, the American
pioneer in the employment of high-pressure steam. A similar idea,
employing an isosceles linkage, was patented in 1803 by William
Freemantle, an English watchmaker (fig. 14).[31] This is the linkage
that was attributed much later to John Scott Russell (1808-1882), the
prominent naval architect.[32] An inconclusive hint that Evans had
devised his straight-line linkage by 1805 appeared in a plate
illustrating his _Abortion of the Young Steam Engineer's Guide_
(Philadelphia, 1805), and it was certainly used on his Columbian engine
(fig. 15), which was built before 1813. The Freemantle linkage, in
modified form, appeared in Rees's _Cyclopaedia_ of 1819 (fig. 16), but
it is doubtful whether even this would have been readily recognized as
identical with the Evans linkage, because the connecting rod was at the
opposite end of the working beam from the piston rod, in accordance with
established usage, while in the Evans linkage the crank and connecting
rod were at the same end of the beam. It is possible that Evans got his
idea from an earlier English periodical, but concrete evidence is
lacking.

[Footnote 31: British Patent 2741, November 17, 1803.]

[Footnote 32: William J. M. Rankine, _Manual of Machinery and Millwork_,
ed. 6, London, 1887, p. 275.]

[Illustration: Figure 14.--Freemantle straight-line linkage, later
called the Scott Russell linkage. From British Patent 2741, November 17,
1803.]

[Illustration: Figure 15.--Oliver Evans' "Columbian" engine, 1813,
showing the Evans, or "grasshopper," straight-line linkage. From
_Emporium of Arts and Sciences_ (new ser., vol. 2, no. 3, April 1814,
pl. opposite p. 380).]

[Illustration: Figure 16.--Modified Freemantle linkage, 1819, which is
kinematically the same as the Evans linkage. Pivots _D_ and _E_ are
attached to engine frame. From Abraham Rees, _The Cyclopaedia_ (London,
1819, "Parallel Motions," pl. 3).]

If the idea did in fact originate with Evans, it is strange that he did
not mention it in his patent claims, or in the descriptions that he
published of his engines.[33] The practical advantage of the Evans
linkage, utilizing as it could a much lighter working beam than the Watt
or Freemantle engines, would not escape Oliver Evans, and he was not a
man of excessive modesty where his own invention