And 1: It confirms _ad oculum_ our former Doctrine, that the falling and rising of the _Mercury_ depends upon the varying weight of the Atmosphere; since in this Baroscope it cannot {237} be pretended, that a _Fuga vacui_, or a _Funiculus_, is the cause of the changes, we observe. 2. It shews, that not only the Air has weight, but a more considerable one, than some Learned men, who will allow me to have prov'd, it has some weight, will admit; since even the variation of weight in so small a quantity of Air, as is but equal in bulk to an _Orange_, is manifestly discoverable upon such Balances, as are none of the nicest. 3. This _Statical_ Baroscope will oftentimes be more parable, than the other: For many will finde it more easie, to procure a good pair of Gold-scales, and a Buble or two, than a long Cane seal'd, a quantity of _Quick-silver_, and all the other requisits of the _Mercurial_ Baroscope; especially if we comprise the trouble and skill, that is requisite to free the deserted part of the Tube from Air. 4. And whereas the difficulty of removing the _Mercurial_ Instrument has kept men from so much as attempting to do it, even to neighbouring places; the Essential parts of the _Scale_-Baroscope (for the Frame is none of them) may very easily in a little room be carried, whither one will, without the hazard of being spoil'd or injur'd. 5. There is not in _Statical_ Baroscopes, as in the other, a danger of uncertainty, as to the goodness of the Instruments, by reason, that in _these_ the Air is, in some more, and in some less perfectly excluded; whereas in _those_, that consideration has no place. (And by the way, I have sometimes, upon this account, been able to discover by our new Baroscope, that an esteem'd _Mercurial_ one, to which I compared it, was not well freed from Air.) 6. It being, as I formerly intimated, very possible to discover _Hydrostatically_, both the bigness of the Buble, and the Contents of the cavity, and the weight and dimensions of the Glassie substance (which together with the included Air make up the Buble,) much may be discover'd by this Instrument, as to the Weight of the Air, _absolute_ or _respective_. For, when the _Quick-silver_ in the _Mercurial_ Baroscope is either very high, or very low, or at a middle station between its greatest and least height, bringing the _Scale_-Barometer to an exact _AEquilibrium_ (1 with very minute divisions of a Graine,) you may, by watchfully observing, when the _Mercury_ is risen or faln just an inch, or a fourth, of half an inch &c. and putting in the like minute divisions of a Grain to the lighter Scale, till you have again brought the Ballance to an {238} exquisit _AEquilibrium_; you may, I say, determine, What known weight in the _Statical_ Baroscope answers such determinate Altitudes of the ascending and descending Quick-silver in the _Mercurial_. And if the Ballance be accommodated with a divided Arch, or a