872 SEC. 19. EDUCATIONAL APPLIANCES. 



4241. Apparatus, consisting of a ball sliding on a wire and 

 lifting various weights. 



E. Lcybold's Successors, Cologne. 



Molecular Physics. 



4242. Stop-cock Air- Pump, with horizontal cylinder and 

 gauge ; can be put in motion by a movement. 



4243. Hand Air-pump, with oblique cylinder, and gauge. 



4244. Pair of Magdeburg Hemispheres, 105 mm. in dia- 

 meter. 



4245. Mercury Granulation Apparatus. 



4246. Apparatus for showing the equal Pressure of the 



Air in all directions. 



4247. Windmill-sail Apparatus, for showing the resistance 

 of the air. 



4248. Apparatus for explaining the Aneroid Barometer 

 and Spring Manometer. 



E. LeybolcVs Successors, Cologne. 



Heat. 



4249. Steam Apparatus, of copper, on supports of brass. 



4250. Aeolipila, on stand. 



4251. Model of a Steam Engine, with oscillating cylinder. 



4252. Rotating Steam Ball. 



4253. Apparatus for explaining the effects of Steam. 



4254. Contraction Apparatus. 



4255. Pyrometer, according to Muschenbrock. 



4256. Mirror Pyrometer, according to Tyndall. 



4257. Apparatus for converting work into heat. 



4258. Woe's Thermochain, star form. 



E. Ley hold's Successors, Cologne. 



Magnetism. 



4259. Graphite Zinc Element, consisting of graphite plate, 

 clay-cell, and zinc cylinder. 



Height of the clay-cell 78 millimeter. 



104 



130 



156 



^l_/O 



