Figure 13.—James White's hypocycloidal straight-line mechanism, about 1800. The fly-weights (at the ends of the diagonal arm) functioned as a flywheel. From James White, A New Century of Inventions (Manchester, 1822, pl. 7).
The first of the non-Watt four-bar linkages appeared 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.
[ [31] British Patent 2741, November 17, 1803.
[ [32] William J. M. Rankine, Manual of Machinery and Millwork, ed. 6, London, 1887, p. 275.
Figure 14.—Freemantle straight-line linkage, later called the Scott Russell linkage. From British Patent 2741, November 17, 1803.
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).
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).