] 
( 74® ) I 
will only rife to Tome height as FC, lefs than the entire 
height of the Tube B C. I 
This Siphon being fill’d with Water, and the Orifice ! 
A funk below the Surface of the Water DE, my Friend i 
reafons thus. 
Since the two Columns of Water AB and FC, by 
the Supppfitiori, will be fufpended by (bme Power adling 
within the Tubes they are contain’d in, they cannot de- 
termine the Water to move one way, or the other. #3uc j 
the Column B F, having nothing to fupport it, mult j 
defcend, and caufe the Water to run out at C. Then 
the prefTure of the Atraofphere driving the Water up- 
ward through the Orifice A, to fupply the Vacuity, 
which would otherwife be left in the upper part of the 
Tube B C, this muft neceflarily produce a perpetual 
Morion, fince the Water runs into the fame Veflel, 
out of which it rifes. But the Fallacy of this reafoning 
appears upon making the Experiment. i 
Exp.i^ For the Water, inftead of running out at |i 
the Orifice C, rifes upward towards /^, and running all f 
out of the Leg B C, remains fufpended in the other || 
Leg to the height A B. 
Exp. 2 . The fame thing fucceeds upon taking the 
Siphon out of the Water, into which its lower Orifice 
A had been immerft, the Water then falling in drops 
out of the Orifice A, and (landing at lad at the height 
AB, But in making thefe two Experiments it is ne- 
cefiary that A G the difference of the Legs exceed FC, [ 
otherwife the. Water will not run either way. ! 
Exp. Upon inverting the Siphon full of Water, it 
continues without Motion either way. i 
The reafon of all which will plainly appear, when 1 
we come to difeover the Principle, by which the Water 
is fufpended in Capillary Tubes. 
Mr. 
