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equiponderant; but if the new Medium be heavier, the greater Body, as being lighter in Specie, will loose more of its weight, than the lesser and more compact; but if the new Medium be lighter than the first, then the bigger Body will outweigh the lesser: And this disparity, arising from the change of Medium's, will be so much the greater, by how much the greater inequality of bulk there is between the Bodies formerly equiponderant. 3.That, laying these two together, I consider'd, that 'twould be all one, as to the effect to be produced, whether the Bodies were weighed in Medium's of differing gravity, or in the same Medium, in case its (specifick) gravity were considerably alter'd; And consequently, that since it appear'd by the Baroscope, that the weight of the Air was sometimes heavier, and sometimes lighter, the alterations of it, in point of gravity, from the weight, it was off at first counterpoising of the Buble of it, would unequally affect so large and hollow a Body, as the Buble, and so small and dense a one, as a Metallin weight; And when the Air by an increase of gravity should become a heavier Medium, than before, it would buoy up the Glass more than the Counterpoise; and if it grew lighter, than it was at first, would suffer the former to preponderate: (The Illustrations and Proof can scarce be added in few words; but, if it be desired, I may, God permitting, send you them at my next leasure:) And though our English Air be about a thousand times lighter, than water, the difference in weight of so little Air, as is but equal in bulk to a Buble, seem'd to give small hopes, that it would be sensible upon a Ballance; yet, by making the Buble very large and light, I supposed and found the Event, I have already related.
Secondly, The hermetically seal'd Glass-buble, I employed, was of the bigness of a somewhat large Orange, and weigh'd about 1. drachme and 10 grains. But I thought it very possible, if I had been better furnish't with conveniences (wherein I afterwards found, I was not mistaken) to make (among many, that might be expected to miscarry) some, that might be preferable to this, either for capacity or lightnes, or both; especially if care be taken, that they be not seal'd up, whilst they are too hot. For, though one would think, that it were advan-
