I. SPECIAL COLLECTIONS. 115 



237. Ratchet train of Langen. 



Used in gas engines. 



238. Turning ratchet gear (Maltese cross wheel). 



239. Turning ratchet gear (incomplete cross wheel). 



240. Turning ratchet gear (spur wheel). 



241. Ratchet train. 



"With automatic disengagement. 



242. Ratchet train, with pin teeth. 



"With automatic disengagement. 



243. Ratchet train (Reed). 



With automatic disengagement and fall. 



244. Ratchet train, with fast click. 



245. Single acting ratchet train. 



The direction of motion can be altered. 



246. Double acting ratchet train. 



247. Reversing ratchet train (Francis). 



Used for governors. 



248. Dividing machine (Nasrnyth). 



249. Lagarousse ratchet gear. 



With eccentric. 



250. Crown wheel ratchet train. 



251. Tooth ratchet train, with double acting free click. 



Model illustrating action of a force pump. 



252. Escapement train (Mudge). 



Can be held in the stand, No. 32. 



253. Throttle click train. 



Illustrates the action of the throttle valve. 



254. Ratchet train, with pinching clicks. 



255. Ratchet train, with several clicks. 



256. Ratchet train, with free clicks. 



Directing gear can be added so as to illustrate the action of a 

 steam engine. 



257. Ratchet train, with fast clicks. 



258. Ratchet train, with Farcy's director. 



259. Ratchet train, with Watt's director. 



Watt's automatic valve gear. 



260. Double acting ratchet gear. 



261. Ratchet train, with cataract director (Hoffmann). 



262. Double acting ratchet gear. 



(Keuleaux.) Shows that the steam engine is a ratchet train. The 

 model can be worked with various forms of directing gear ; it stands 

 upon a large mahogany frame with columns. 



263. Apparatus for using with Nos. 244 to 254 : Column with 



fly wheel and two connecting rods. 



H 2 



