XI. MODELS, ETC. 467 



2250. Reversing Motion, with two and three spur wheels 

 (quick return). 



2251. Reversing Motion with Clutch. 



2252. Model of Train of Wheels. 



2253. Specimen of Spur Wheel. 



2254. Two Models of Slit-bar Motion. 



2255. Application of Slit Bar Motion in Whitworth's 

 shaping machine. 



2256. Two Models of Ratchet Wheels. 



2257. Masked Ratchet Wheel. 



2258. Silent Ratchet Wheel. 



2259. Model to show Advance of a Ratchet Wheel 

 through part of the Space of a Tooth. 



2260. Ratchet Wheel, for traversing the cutter in a planing 

 machine. Clement's Click. 



2261. Machine for Printing Numbers. 



2262. Drawing of a Lathe. (Whitworth.) 



2263. Drawing of a Planing Machine. (Whitworth.) 



2264. Apparatus to show that Friction is independent 

 of Velocity. 



2265. Apparatus to illustrate Friction Grips, and for 



experiments on the laws of friction. 



2266. Model to show when a Drawer jams. 



2267. Model to explain Weston's Friction Clutch. 



2268. Silent-feed Motion (Worssam). 



2269. Apparatus for illustrating the Angle of Repose 

 between Two Surfaces. 



2270. Plummer Block, showing Cylindrical Bearing. 



2271. Form of Conical Bearing. 



2272. Model of Friction Wheels. 



2273. Model of Single Pulley Block. 



Gg 2 



