equiponderant ; but if the new Medium be heavier, the greater 
Body, as being hghter in Specie^ will loofe moreof its weight, 
than the lefler and more compad 5 but if the new Medium be 
hghter than the firft, then the bigger Body will outweigh the 
lefler : And this difparity, arifing from the change of Medium\ 
will be fo much the greater, by how mnch the greater inequality 
of bulk there is between the Bodies formerly equiponderant. 
3. That, laying thefe two together, I confider^d^ that 'twould 
be all one^ as to the efFe£t to be produced, whether the Bo- 
dies were weighed in M^^s^^Ws of differing gravity, or in the 
hmt Medium^ in cafe its {fpecificJQ gravity were confidsrably 
alter'd: And confequcntly, that fince it appeared by the ^B^- 
rofcope, that the weight of the Air was fometimes heavier, and 
fometimes lighter, the alterations of it,- in point of gravity, 
from the weight, it was off at firft counterpoifing of the Buble 
of it, would umquaUy affect fo large and hollow a Body,as the 
Buble, and fo fmall and denfe a one^ as a MetaUin weight : And 
when the Air by an increafe ©f gravity fliould become a heavier 
Medium^ than before, it would buoy up the Glafs more than 
the Counterpoifei and if it grew lighter^ than it was at firft, 
would fuffer the former to preponderate : ( The Illuftrations 
and Proof can fcarce be added in few word^ j but, if it be de- 
firedj I may, God permitting, fend you them at my next lea- 
fure : ) And though our Eng'lifh Air be about a thoufand times 
lighter, than water^ the difference in weight of fo little Air, as 
is but equal in bulk to a Buble, feem'd to give fmall hopes, that 
it would be fenfible upon a Ballance ; yet, by making the Buble 
very large and light^ I fuppofed and found the Event, I have 
already related. 
Seeondly, The hermetically feal'd Glafs-buble, I employed, 
was of the bignefs of a fomewhat large Orangey and weighed 
about r . drachme and lo.grains. But I thought it very poffible^ 
if I had been better furnifli t with conveniencies (wherein I af- 
terwards found, I was not miftaken ) to make (among many, 
that might be expected to mifcarry) fome,that might be pre- 
ferable to this, either for capacity or lightnes, or both; efpe- 
cially if care be taken, that they be not fcaM up, whilft they 
are too hot. For^ though one would think, that it were advan- 
tagious 
