An historical and philosophical account of the barometer, or weather-glass ... And a modest attempt from thence made towards a rational account and probable judgement of the weather / By Edw. Saul, A.M.

  • Saul, Edward, 1677-1754.
Date:
1730
Catalogue details

Licence: Public Domain Mark

Credit: An historical and philosophical account of the barometer, or weather-glass ... And a modest attempt from thence made towards a rational account and probable judgement of the weather / By Edw. Saul, A.M. Source: Wellcome Collection.

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    and, in Proportion as the Weight decreafes by the Air fucceeding in its Place, the Quick-Silver in the Tube will gradually defcend, and fettle as before, to its lower Station. From thefe E xperiments, and the Con- clufions grounded upon them, it is to De- monftration evident, that the general and perpendicular Preifure of the incumbent Air, or Atmofpbere, upon the Surface of the Earth, is the Force that raifes up the Mer¬ cury in the empty Tube ; that the very fame Preifure of the Air, is the Counterpoife that fupports the Mercury at its proper Height; and that they are only the various Changes in the Gravitation of the Air, that produce the correfpondent Changes in the Rife and Fall of the Mercury. From hence alfo it appears, that the little Vacuity in the upper Part of the Tube, is in reality the main Spring and Engine that keeps the Barometer in play ; that diredts and determines the general Preifure of the Air, to its particular Ufe and Service ; and even confines it to difeover the daily Chan¬ ges it undergoes in its own Gravity, by bringing it there to the Teft, and weighing in a Philofophical Ballance, a Column of Air, againft a Cylinder of Quick-Silver. F o r if you break the Tube, and deftroy the Vacuum in the upper Extremity, by letting in the outward Air, you deftroy the C 2 Ballance,