( it 7 ) 
pen at both Ends, and cemented tight to the Neck of 
the Bottle at C •, then having warm’d the Bottle with 
the Hand to drive Come of the Air out of it, he immerges 
the End A into Water, ting’d with Cochineal ^ fo that 
as the Air cools in the Bottle C B, fome of the red Wa- 
ter is forc’d into the Bottle then fetting the Bottle 
upright again, as in the Figure, the Liquor in the Bot- 
tle will hand at B, (above the End of the Tube) and 
that in the Tube at D ; but if it fliou’d hand higher or 
lower than D, it may be brought to that Place by fuck- 
ing or blowing at A. The Inftrument, thus prepar’d, if 
it be firft feton the Ground, and a fp'ringingRing of fine 
Wire Hipp’d on the Tube down to D, by Way of Index, 
and then fet upon any Table, or other Place, . lcarce 
a Yard higher, one may obfervethat the Liquor is rifen 
fenfibly. ' I havefeen it rife a Quarter of an Inch, when 
the Bottle was fet but a \ r ard higher than where it flood 
before fo that the Column of Atmofphere, that prefs’d 
down the Tube, whilft the Machine was on the Ground, 
bein* fhortend only three Feet, was fo overbalanc’d by the 
Expanfion of the Air in the Bottle at B, that the Liquor 
rofe a Tenth of an Inch above D. There is, indeed, a 
great Uncertainty in this Inflrument j for fmee it is a 
Thermometer, as well as a Barometer, the Warmth of 
the Hand that touches it, or even comes near it, will 
make it rife, if the Air in the Bottle was cold before. 
Mr. Gray therefore contriv’d to put the Bottle C B, 
into the Veffel F E, which he fill’d with Sand j that in 
railing the Inftrument, and moving it up and down, the 
Air in C B might continue in the fame State, and the 
Machine be only a Barometer during the Experi- 
ment. 
B 
This 
