( 5t58 ) 
Air was thus rarifyed, yet when the abfeoce of the Sud, or 
uuy other caufe made the Air loofe its Adventitious 
wartntbj there would enfue a Gbndenfatioa of the Air a- 
gaioj and thereupon an lotrufion of more Water (to fuc- 
eeed the Air) into th« Glafs, and confcqucntly a fiokiog of 
the Bubble, and this would commonly happen at night , if 
it did not happen foonen But when 'twas upon the ac- 
count of the Varying Weight of the Atmofphere that the 
Bubbles either rofe or fell , it appear'd by the Barofcope^ 
that the Atmofphere was (o heavy or fo light, that they 
ought to do fo. Infomuch that t divers times predidled, 
whether 1 (bould find the Mercury in the Barofcope high 
or low, by obferving the Situation and pofture of the Bub- 
bles i and confuting that Inftrument, it verified my Gon- 
jeftures. And though^ whilft the Atmofphere was not too 
coofiderably either light or heavy^ the Changes of the Air 
as to Heat or Gold^ would (as I was faying) place the Bub- 
bles fometiroes at the top and fomctimes at the bottom of 
the Water, within the compafs of a day ; yet if the Atmo- 
fphere were either very heavy or very light, the bubbles* 
would continue at the bottom or at the top of the Water 
for many daies together in cafe the Atmofphere did not in 
all that time change its Gravity* And I remember, that 
I<lid ^ for curiofities fake, when the Quickfilvcr was high^ 
in the Barofcope , put the Glafs two or three daies in a 
South-window about Noon ( and for a good while after ) 
and that in Sun-fhining weatherjand yet even then the Bub- 
bles did not emerge, though it appear'd by a good fealcd 
Weather-glafi, which I kept in the fame Windowjthat the 
ambient Air was much warmer than at other times ^ when I 
bad obferved the Bubbles to keep at the top of the Water, 
NB; I. It being very difficult to poife feveral Bubbles 
prccifelyj as well one as another, I thought it not ftrange, 
that all the three Babbles did not conftantly ( though for 
the moft part they did ) rife and fall together, butfome- 
timestwo of them .;, and nowmd then (though feldome)' 
mc aiode would fiEk^oi emerge ^ when the change of iht 
weight 
i 
