X 
I 274 ) 
CHAP. m. 
Experiments, Jhemng the Force of the Rife of the Sap in 
the Vine, in the Bleeding Seafon* 
M r. Hales, by a very curious Contrivance of 
Glafs-Tubes, ferew’d and cemented at the top 
of one another, and altogether fixed to the Stem of a 
Vine, obferv*d,that in the bleeding Seafon (a;/2. iKsMarch 
April) t\iQ Sap will rife into the Tubes, by the force 
of the Roots and Stem, to very great heights, even a- 
bove the Top of the Vine, as it did up to the Top of a 
Tube 15” Feet high (in two Hoursj and ran out at the 
laid Tube, tho’ 7 Feet above the Top of the Vine* 
But the Force was fuch, that the Mercury, in a Gage 
(in other Experiments) was pulh'd up 31*- Inches 
high, which was equivalent to above 45 Feet of Wa- 
ter. This is a much greater Force than the Blood is 
impell’d with in Animals : Which laft Force he tried 
in the Crural Artery of an Horfe, of a Dog, and of 3 
Deer : For having tied them down alive upon their 
Backs, and fixed a Glafs-Tube to the Crural Artery o- 
pen’d, he found, that in the Horfe the Blood rofe a- 
bove 8 Feet, in the Dog about 7 Feet, and in the Deer 
not quite 6 ; And thefe Heights are 5, 7, and 8 times 
lefs than the Height to which the Sap is raifed by the 
Vine. The Sap rifes all Night, but moft in the Mor- 
ning of a warm Day ; but in very hot Weather it 
ceafes to rife about Ten in the Morning, and then be- 
gins again to rife about 3 or 4 in the Afternoon ; and 
during the great Heat, Bubbles of Air drawn in by the 
Roots, come up the Tube from the Sedion of the Stem, 
the Sap in the Tube finking and rifing. as the Weather is 
cloudy or dear, like the Liquor in a Thermometer. 
That 
