C 353 J 
during the fpace of 35 minutes of time, from the 
inftant of its being fet up till it had loft the circular 
motion : but we found, that in the exhaufted receiver 
it played or fpun during the fpace of two hours 16 
minutes * ; and therefore, that the air has no fhare 
at all of the caufe of its horizontality, and that the 
air is a great impediment to its motion. 
London, Feb. 6 , 
1752. 
Ja. Short. 
LVII. Obfervations ?nade in going up the Pic 
of Teneriffe, by 2)r. Thomas Heberden, 
and communicated hy William Heberden, 
M. D. R R. S. 
Read Feb. 6, 
1752. 
A T two of the clock in the after- 
noon we fet out from the villa or 
town of Orotava, about 6 leagues diftant from the 
Pic of Teneriffe. The weather was cloudy ; and 
before we had tra veil’d quite a league, we found 
ourfelves furrounded by a very thick mift or fog, 
which lafted about a league : all which time we tra- 
veled among gardens and woods of pine-trees, after 
which we came to an open country ; the foil very dry j 
here and there a ftngle pine-tree, and fome few Spaniih 
broom -pi ants ; fome loofe large ftones, of the bignefs 
of a butt ; others, which teem’d to have been burned, 
and are fuppofed to be caft out from the vulcano of 
the Pic. The iky very clear, and the thick miff, which 
we had pafled thro’, now feern'd a fea of afti-colour’d 
Y y clouds 
* Preferving a perfcft horizontality fqr the fpace of 4 of an hour. 
