C 5^58 ) 
;Air w^s thiis rarifyed, yet when the abfenee of the Siio, or 
my other caufe made the Air loofe its Advcatidoas 
v/armthj there would enfiie a CoDdenfatioo of the Air a- 
gain, aad thereupon an Idtrufion of more Water (to fuc- 
ceed the Air) into the Olafs, andconfcquently a fiokiogof 
the BubbJej and this would commonly happen at night , if 
it did not happen foonen But when 'twas upon the ac- 
count t)f the Varying Weight of the Attnofphere that the 
Bubbles either rofe or fell , it appeared by the Barofeope, 
that the Atmofphere was fo heavy or fo light, that they 
cught to dofo. infomuch that T divers times predicfted,^ 
whether I ffiould find the Mercury in the Barofcope high 
or low, by obferving the (cituation and pofture of the Bub- 
bles 5 and confulting that Inftrumenr, it verified my Goo^ 
jeftures. And thougb^ whilft the Atmofphere was not roa 
confiderabiy either light or heavy, the Changes of the Air 
as to Heat or Gdld, would (as I was faying) place the Bub- 
bles fomecimcs at the top and fornctimes at the bottom of 
the Water, within the cqmpafs of a day ; yet if the Atmo- 
fphere were either very heavy or very lights the bubble^ 
would continue at the bottom or at the top of the Water 
for many daies together in cafe the Atmofphere didDOtin 
all that time change its Gravity. And I remcmberi that 
I did, for curiofities fake, when the Quickfilver was high 
in the Barofcope, put the Glafs two or three daies in a 
• S^auth-'Window about Noon ( and for a good while after ) 
and that in Sun fliining weather j^nd yet even then the Bub- 
bles did not emerge^ though itappear'd by a good fealed 
Wcather-glais^ which I keptin the fame WinddWjthat the 
ambient Air was much warmer than at other times 5 when f 
had obferved the Bubbles to keep at the top of the Watef. 
N B. ^ , It being very difficult to poife fevcral Bubbles 
precifelyj^ as well one as another, I thought it not ftraoge,^ 
rhat all the three Bubbles did not conftantly ( though for 
ihe moft part they did ) rife acd fall together 5 but foffie- 
limcstwa of them ^ and now and then (though feldonie) 
mQ alfse would fink or emerge^ whtn the change of the 
weight 
