1048 SEC. 19. EDUCATIONAL APPLIANCES. 



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. Ley hold's Successors, Cologne. 



Heat. 



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



50 SO. Aeolipile, on stand. 



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



4252. Rotating Steam Ball. 



4253. Apparatus for explaining the effects pf Steam. 



4254. Contraction Apparatus. 



4255. Pyrometer, according to Muschenbrock. 



4256. Mirror Pyrometer, according to Tyndall. 



4257. Apparatus for converting work into heat. 



4258. Noe's Thermochain, star form. 



E. LeybolcVs Successors, Cologne. 



Magnetism. 



4259. Graphite Zinc Element, consisting of graphite plate, 

 clay-cell, and zinc cylinder. 



Height of the clay-cell 78 millimeter. 

 ?j 104 



130 

 156 



208 



260 



4260. Chromic Acid Element, small, bottle-shaped, with 

 two graphite and one zinc plate. 



4261. Chromic Acid Element, larger, with two graphite and 

 one zinc plate. 



4262. Chromic Acid Element, with three zinc and one 

 graphite plate. 



4263. Coal-light Apparatus, with small reflector (hand re- 

 gulator). 



