Dr. Hare’s Improved Barometer Gage Eudiometer. 281 
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Description of the Gage. 
It is well known, that if a vertical glass tube communicate, through 
its upper orifice, with a receiver, while its lower orifice is 
beneath the surface of an adequate quantity of mercury, in any con- 
venient receptacle; on exhausting the receiver, the metal will rise 
in the bore of the tube in proportion to the quantity of air removed. 
Hence, if zero of the ascending column of degrees, counting upwards 
from one to ten, be placed on a level with the surface of the mercury 
in the receptacle at the foot of the gage tube G, the quantity of gas 
liquefied or withdrawn will be as the number of degrees opposite 
the surface of the column of the mercury in the gage tube. 
Again, supposing it were possible to exhaust the vessel perfectly, 
the column of mercury in the gage, would attain the height of a well 
filled Torricellian tube. By having such a tube by the side of the 
Vou. XXXII—No. 2 36 
