Vegetable Stanch . 39 
“ Frozen concave clouds therefore, by their 
u great reflexions, produce a vigorous heat, 
and the fame when refolved exceffivc 
c< cold. 
Whence we fee that Wafts may be occa- 
fioned by the refleXions of the clouds, as 
well as by the above mentioned refraXion 
of denfe tranfparent vapors. 
July 21, I obferved that at that feafon 
the top of the Sunflower being tender, and 
the flower near beginning to blow, that if 
the Sun rife clear the flower faces towards 
the Eaft 5 and the Sun continuing to fhine, 
at noon it faces to the South; and at fix in 
the evening to the Weft : And this not by 
turning round with the Sun, but by Nuta- 
tion 5 the caufe of which is, that the fide 
of the ftem next the Sun perfpiring 1110ft, it 
fhrinks, and this plant perfpires much. 
I have obferved the fame in the tops of 
Jerufalem- artichoke S) and of garden-beans, 
in very hot Sun-fhine. 
Experiment X. 
July 27. I fixed an Apple-branch, m, 3 
feet long, ~ inch diameter, full of leaves, 
D 4 and 
