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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    are plainly produc’d by the Spring of the Air: But then, the regular and fteady Set¬ tlement of the Mercury to its proper Stan¬ dard, is certainly owing to a Caufe equally fteady and regular ; that of the perpendi¬ cular Weight and Preffure of the Air afting upon it, and by Degrees checking the Vi¬ brations caus’d by the Spring of the Air, ’till they come to an AEquilibrium. I f we purfue this Experiment ftill far¬ ther, with a Tube open at both Ends, and fufpended in the ftagnant Mercury ; the Mer¬ cury will remain at the fame Height in the Tube, and in theCiftern. Then fix a clofe Co¬ ver, as well round the Tube, as over the Top of the Ciftern ; and confining there, within the cover’d Space, a fmall Quantity of com¬ mon Air, (without any Communication with the external Air) and place the whole Appara¬ tus, thus order’d in the Air Pump. TheEffeQ: will be this; that by working the Pump, and exhaufting the Receiver, the Counter-Pref- fure of the external Air will be quite taken off; and then, the Air enclos’d within the co¬ ver’d Ciftern, will dilate and expand itfelf; and by its elaftic Preffure upon the ftagnant Mercury, will raife and force it up within the Tube, to the Height of 28 t, or 29 Inches, according to the Standard of the Barometer in the open Air, but no higher. From hence it is evident. 1 /?, That the Weight of the Air, is here entirely fe- pa rated