The Whitworth quick-return mechanism (fig. 44) was first applied to a slotter, or vertical shaper, in 1849, and was exhibited in 1851 at the Great Exhibition in London.[109] Willis' comments on the mechanism are reproduced in figure 44. I hope that Sir Joseph Whitworth (1803-1887) will be remembered for sounder mechanical contrivances than this. [Footnote 109: The quick-return mechanism (British Patent 12907, December 19, 1849) was perhaps first publicly described in Charles Tomlinson, ed., _Cyclopaedia of Useful Arts and Manufactures_, London, 1854, vol. 1, p. cxliv.] [Illustration: Figure 44.--Quick-return mechanism. _Top_, Early representation of the quick-return mechanism patented by Whitworth in 1849, from William Johnson, ed., _The Imperial Cyclopaedia of machinery_ (Glasgow, about 1855, pl. 88). _Middle_, Sketch by Robert Willis from his copy of _Principles of Mechanism_ (London, 1841, p. 264), which "shews Whitworth dissected into a simpler form"; it is as obscure as most subsequent attempts have been to explain this mechanism without a schematic diagram. _Bottom_, Linkage that is kinematically equivalent to Whitworth's, from Robert Willis, _Principles of Mechanism_ (London, 1841, p. 264).] Mechanisms in America, 1875-1955 Engineering colleges in the United States were occupied until the late 1940's with extending, refining, and sharpening the tools of analysis that had been suggested by Willis, Rankine, Reuleaux, Kennedy, and Smith. The actual practice of kinematic synthesis went on apace, but designers often declined such help as the analytical methods might give them and there was little exchange of ideas between scholars and practitioners. The capability and precision of machine tools were greatly enhanced during this period, although, with the exception of the centerless grinder, no significant new types of tools appeared. The machines that were made with machine tools increased in complexity and, with the introduction of ideas that made mass production of complex mechanical products economically feasible, there was an accelerating increase in quantity. The adoption of standards for all sorts of component parts also had an important bearing upon the ability of a designer economically to produce mechanisms that operated very nearly as he hoped they would. The study of kinematics has been considered for nearly 80 years as a necessary part of the mechanical engineer's training, as the dozens of textbooks that have been published over the years make amply clear. Until recently, however, one would look in vain for original work in America in the analysis or rational synthesis of mechanisms.