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Intelligence and Miscellanies. 



1 6. Engraving mid description of the Hydro-Pneumatic Cis- 

 tern, used in the Laboratory of the University of Pennsyl- 

 vania ; by R. Hare, M. D. Professor of Chemistry. 



Fig. 1. 



This engraving is intended to convey an idea of my Hydro- 

 Pneumatic Cistern. It is constructed upon the principle of 

 one contrived by Professor Silliman and myself, when we 

 operated together in 1 803, and which we have used under 

 various modifications, since that time. 



The figure, here given, is such as would be presented to 

 the eye, were the front of the cistern removed. 



A A, are two shelves formed by two inverted chests, which 

 are used as cells to contain gas : B is a sliding shelf, over a 

 deep place between the shelves A A, which is called the well 

 of the cistern. 

 Fig. 2. 



Fig. 2 affords a view of the lower 

 side of the sliding shelf, in the wood 

 of which it will be seen that there 

 are two excavations, converging 

 into two holes, one of which is 

 seen at h, fig. 1 . This shelf is loaded with an ingot of lead 

 at L, to prevent it from floating in the water of the cistern. 



Besides the chests above mentioned, there are two others, 

 C C, near the bottom of the cistern, but not so close as to 

 prevent the water from passing freely into and out of them. 



