Ch3] 
Then pour into theCane B C as much Spirit of Wine tinged 
! with CochineeUy and Oyleof Tur^entine^^c^dW parts ofeach,as 
(hall ftand above the furface of the Mercury fo many feet as 
you make the enlarged fcale of your Barometer, or as is be* 
tween the middle of the Cylinders B and C, and you will find 
the Mercury link in the Cane BC, and Rift in the other 
Cane A D, in fucii proportion, that each 1 3 foot of Oyle and 
Spirit, will raiie the iC .ercury ten Inches : This done, you 
muft pour on, bv the C ane B C,fo much Mercury as may fill 
up the Cylinders A & B to fueh hights, confidering the prefent 
weight of the Atmofpiiere, that the furface of the Mercury 
in both, may , at the utmcft limits, ( which have not in Eng- 
been found to exceed 30, 6 and 28, 6. Inches^ always 
fall within the bodies of the Cylinders, and never enter into 
the Canes. 
Here note that thefe Liquors are chofen upon two accounts, 
Firft they are exceeding near of a weight, and Spirit of Wine 
highly redified is fbmewhat lighter than Oyle of Turpentine, 
but by a very finall addition of Phlegme or Water, the Spi- 
rit will prgeponderate and be undermoft ; fo that you may 
make them as near ofa weight as you pieafo, and confequent- 
lya Cylinderof the Oyle inlenfibly differing from an equal 
Cylinder of Spirit of Wine. Secondly they are Liquors that 
will not mix ; fo that the Oyle of Turpentine fiviming on 
the top, will be divided by a line only from the tinged Spirit 
of Wine, which the Oyle will keep from Evaporating, 
The effcd of this Barofocpe will be, that when the Atmos- 
phere is heavy, and the Mercury railed high in the Cylinder 
A, and retired out of B, the Spirit of Wine will defoendinto- 
the Cyhnder B, and the Oyle of lurpentine will fill the Cane, 
fo as to make the partition of the two Liquors near the Cy- 
linder B. But on the contrary when the Air is light, the Mer- 
cury will fink in A and rife in B, fo as to drive the Spirit or 
Wine into the Cane, and the Oyle of Turpentine into t\\t 
\ Cylinder C, fo that the feftion of the 2 Liquors will be near 
CJ, aad the Variation of the hight of the Mercury will be en- 
