Figure 40. — Geneva stop mechanism 

 first used in Geneva watches to pre- 

 vent overwinding. The starwheel B 

 had one convex surface {g-f, dotted) so 

 the wheel could be turned less than a 

 full revolution. After Robert Willis, 

 Principles of Mechanism (London, 1841, 

 p. 266). 



years designing coaches for English gentlemen in 

 London, where he made his home. One of his more 

 notable cominissions was for the design of Admiral 

 Nelson's funeral car in 1 805. The Ackermann steering 

 linkage was not actually Ackermann's invention, 

 although he took out the British patent in his name 

 and promoted the introduction of the running gear 

 of which the linkage was a part (fig. 43). The actual 

 inventor was Ackermann's friend George Lanken- 

 sperger of Munich, coachmaker to the King of 

 Bavaria. The advantage of being able to turn a 

 carriage around in a limited area without danger of 

 oversetting was immediately obvious, and while 

 there was considerable opposition by English coach- 

 makers to an innovation for which a premium had 

 to be paid, the invention soon "made its way from 



Figure 41. — Scotch yoke, described as a "crank 

 and slot-headed sliding rod." From W. J. M. 

 Rankine, A Manual of Machinery and Millwork 

 (ed. 6, London, 1887, p. 169). 



its own intrinsic merit," as Ackermann predicted 

 it would.'"* 



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 Exhibi- 



ts Rudolph Ackermann, Observations on Ackermann's Patent 

 Moveable Axles, London, 1 819. It was interesting to me to note 

 an abstract of W. A. Wolfe's paper "Analytical Design of an 

 Ackermann Steering Linkage" in Mechanical Engineering, Sep- 

 tember 1958, vol. 80, p. 92. 



Figure 42. — A "Scotch" supporting 

 the top member of a string of well- 

 drilling tools while a section is being 

 added, 1876. From Edward H. 

 Knight, Knight's American Mechanical 

 Dictionary (New York, 1876, p. 2057). 



222 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



