WITH WHICH AIR RUSHES INTO A VACUUM, 



149 



the above pressure. The accuracy of this gauge was 

 tested in my presence by the constructors, Messrs. 

 Budenberg and Co., through the whole range of pressure. 



by comparing its readings with a column of mercury of 

 equivalent height. For pressures of 15 pounds above, and 

 for pressures below the atmosphere, a mercurial gauge and 



