Wheel and Index, these Observations will assist you for the future to determine readily, by seeing the inclination of the Cock or the degree mark'd by the Index, what pollency the Buble hath, by the change of the _Atmospheres_ weight, acquired or lost. Some Observations of this nature I watchfully made, sometimes putting in a 64^{th.} sometimes a 32^{th.} sometimes a 16^{th.} and sometimes heavier parts of a Grain, to the lighter Scale. But one, that knew not, for what uses those little papers were, coming to a window, where my Baroscopes stood, so unluckily shook them out of the Scales, and confounded them, that he robb'd me of the opportunity of making the nice Observations I intended, though I had the satisfaction of seeing, that they were to be made. 7. By this _Statical_ Instrument we may be assisted to compare the _Mercurial_ Baroscopes of _several_ places (though never so distant) and to make some Estimates of the Gravities of the Air therein. As if, for instance, I have found by Observation, that the Buble, I employ, (and one may have divers Bubles of several sizes, that the one may repaire any mischance, that may happen to another) weigh'd just a Drachme, when the _Mercurial_ Cylinder was at the height of 291/2 inches (which in some places I have found a _moderate_ altitude;) and that the Addition of the 16th part of a gr. is requisite to keep the Buble in an _AEquilibrium_, when the _Mercury_ is risen an 8th, or any determinate part of an inch above the former station: When I come to another place, where there is a _Mercurial_ Barometer, as well freed from Air as mine (for that must be supposed) if taking out my _Scale_ instrument, it appeare to weigh precisely a Drachme, and the _Mercury_ in the Baroscope there stand at just 291/2 inches, we may conclude the Gravity of the Atmosphere not to be sensibly unequal in both those two places, though very distant. And though there be no Baroscope there, yet if there be an additional weight, as for instance, the 16th part of a Grain requisite to be added to the Buble, to bring the scales to an _AEquilibrium_, it will appear that the Air at this second place is, at that time {239} so much heavier, than the Air of the former place was, when the _Mercury_ stood at 291/2 inches. But in making such comparisons, we must not forget to consider the Situation of the several places, if we mean to make Estimates not only of the weight of the Atmosphere, but of the weight and density of the Air. For, though the Scales wil shew (as has been said) whether there be a difference of weight in the Atmosphere at the two places; yet, if one of them be in a Vale or bottom, and the other on the top or some elevated part of a Hill, it is not to be exspected, that the Atmosphere, in this latter place, should gravitate as much, as the Atmosphere in the former, on which a longer Pillar of Air does lean or weigh.