Mtfcellanea Curiofa. 85 



Jy the fides, C B, G K> L D, 6cc. are recipro- 

 cally as the fides A A JQ r A L, &c. If then 

 the Lines A B, A K., A L, be fuppofed equal to 

 the heights of the Mercury, or the preffures of 

 the Atmofphere, the Lines C B, G K> L D, aij- 

 (wering thereto, will be as the Expanfions of 

 the Air under thofe Preffures, or the Bulks that 

 the fame quantity of Air will occupy ; which 

 Expanfions being taken infinitely many, and 

 infinitely little, (according to the Method of 

 Indiviiibles) their Summ will give the Spaces 

 of Air between the feveral heights of the Baro- 

 meter i that is to fay, the Summ of all the Lines 

 between C B and J£ G, or the Area C B K^G, 

 wiil be proportioned to the Diftance or Space 

 Intercepted between the Levels of two Places in 

 the Air, where the Mercury would ftand at the 

 heights reprefented by the Lines A B, A , fo 

 then the Spaces of Air anfwering to equal Parts 

 of Mercury in the Barometer, are as the Areas 

 C B K.G, GK.LD, D L FM, &c. Thefe Areas 

 again are, by the Demonftration of Gregory of 

 St. Vincent^ proportionate to the Logarithms of 

 the Numbers exprefiing the \ationes of A to 

 A B, A L to A o£ A M to A L, &c- 

 So then by the common Table of Logarithms, 

 the height of any Place in the Atmofphere, ha- 

 ving any aflign'd height of the Mercury, may 

 moft eafily be found : For the Line C B in the 

 Hyperbola, whereof the Areas defign the Tabular 

 Logarithms, being o, 0144765* ; 'twill be, as 

 o, 0144765', to the difference of the Logarithms 

 of 30, or any other leffer Number, for 900 

 Feet, or the Space anfwering to an Inch of Mer~ 

 cury, if the Air were equally preft with 30 Inches 

 of Mercury , and every where alike, to the 

 height of the Barometer in the Air, where it 

 G % will 



