f^egetahle Stauchl p 
reafon of the reciprocal proportion) that 34. 
cubick inches may pafs the ftem in twelve 
hours 5 whence its velocity in the ftem will be 
45 t inches in twelve hours, fuppofing there 
be no circulation nor return of the fap 
downwards. 
If there be added to 34, (which is the leaft 
velocity) -f of it = 1 1|, this gives the grcateft 
velocity, 'uiz. 45f* The fpaces being as 3 : 
4. the velocities will be 4: 3 : : 45t : 34. 
But if we fuppofe the pores in the fur- 
face of the leaves to bear the fame propor- 
tion, as the area of the fap veftels in the 
ftem do to the area of the ftem 5 then the 
velocity, both in the leaves, root and ftem, 
will be increafed in the fame proportion. 
A pretty exad account having been ta- 
ken, of the weight, fize, and furface of this 
plant, and of the quantities it has imbibed 
and perfpired, it may not be improper here, 
to enter into a comparifon, of what is taken 
in and perfpired by a human body, and this 
plant. 
The weight of a well fized man is 160 
pound : The weight of the Sunflower is 
three pounds, fo their weights are to each 
other as i^o ; 3, or as 53 ; i. 
i 
The 
