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An Epy on the VARIATIONS of the BAROMETER. 

 By RICHARD KIRWAN, Efq-, M.R.LA. and F.E.S. 



XllMONG the various purfuits which for upwards of a century Read March 

 have engaged the attention, and exercifed the ingenuity of the '»'7^^- 

 philofophic world, none has the merit of contributing fo largely 

 to the general ftock of natural knowledge, nor is there any from 

 which mankind has derived fuch extenfive and immediate advan- 

 tage, as from that which has the nature and properties of the atmo« 

 fphere for its objed. To fay nothing of the profound refearches 

 of a Scheele, a Cavendifh or a Prieftley, which have fo happily 

 developed the more fecret and intimate qualities of this invifible 

 fluid, it is from the inveftigation of its more general and obvious 

 properties, its gravitation, denfity and elaflicity, that mechanicks 

 and aftronomy have received many of their greateft improvements. 

 The inftrument which firft led philofophers to fufped, and which 

 at laft fully confirmed the exifience, and even defined the extent 

 and limits of thefe properties, was the barometer. Through it 

 the weight of the whole atmofphere which furrounds the earth, 



G 2 a problem 



