8 s MifceUanea Curio fa. 



quently the Air ratified, when all the(e were 

 tried, we may without (enfible Error fay in 

 round numbers, that the Barometer (landing at 

 30 Inches, and in a mean State of Heat and 

 Gold, the fpecifick Gravity of the Air to Wa- 

 ter, is as 1 to $00. By the like Trials the weight 

 of Mercury to Water, is as Stii to 1, or very 

 near it ; fo that the weight of Mercury to Air, 

 is as 10800 to 1 , and a Cylinder of Air of 

 10800 Inches or 900 Feet, is equal to an Inch 

 of Mercury ; and were the Air of an equal den- 

 fity like Water, the whole Atmofphere would be 

 no more than 1 Miles high, and in the Af- 

 cent of every 900 Feet the Barometer would 

 fink an Inch. But the Expanfion of the Air in* 

 creating in the fame proportion as the incumbent 

 weight of the Atmofphere decreafes ; that is, as 

 the Mercury in the Barometer finks ; the upper 

 Parts of the Air are much more rarified than the 

 lower, and each Space anfwering to an Inch of 

 Quickfilver, grows greater and greater j fo that 

 the Atmofphere muft be extended to a much grea- 

 ter height. Now, upon thefe Principles, to de- 

 termine the height of the Mercury at any ailign- 

 ed height in the Air j and e contra, having the 

 height of the Mercury given, to find the height 

 of the Place where the Barometer Hands, are Pro- 

 blems not more difficult than curious 3 and which 

 I thus refolve. 



The Expanfions of the Air being reciprocally 

 as the heights of the Mercury, it is evident, that 

 by the help of the Curve of the Hyperbola and its 

 Afymptotes , the (aid Expanfions may be expound- 

 ed to any given height of the Mercury : For by 

 the 6*5'th Prop, lib. z. Conic* Mydorgii> the Rg&an* 

 gles, A B C E 9 AKGE> A L D E 9 &c. (hi 

 Plate 1. Fig. 4,) are always equal, and confequent- 



