just the same Force, press against the sides of it. And just so it is in the present Case; where the air so included doth press by its Spring, just with the same Force as was that of the incumbent Air which gave it this Tensure.It is yet the more evident, because if (by the Air-Pump) part of this Air be pumped out, and thereby the rest less compressed; the Quick-silver in the Tube, (in Fig. 37.) will sink from E to a lower Station, as to F or G; and so lower and lower, as more and more Air is pumped out, and the Spring thereby relaxed: That is, as the Spring grows weaker, so it is less able to support the Weight.And this quite destroys the Evasions but now mentioned; That the seeming void space is filled by a thin Substance, which can by the Weight of 29 inches of Quick-silver, or 34 foot of Water, but not by less, be stretched to that fineness; and that therefore it will sink to that height, but not lower.For, by this last Experiment, when the Air is included with its ordinary Tensure, it sustains the Quick-silver at the height of 29 inches; as if less than that Weight were too little to stretch the Quick-silver into that supposed fine substance: But, when that Air, by pumping, is weakned; it will sink to 20, 10, 5, yea less than 1 inch of height; as if now less than the Weight of 1 inch were enough so to stretch it, as less than 29 inches would not do before. Yet is no alteration, all this while, made in the Tex∣ture of the Quick-silver; but in the Tensure of the Air onely. 'Tis therefore from this different Tensure or Spring of the Air, not from any difference in the Quick-silver, that it stands some∣time at a higher, sometime at a lower station.And what hath been thus said of this Torricellian Experiment, is easily applicable to others of like nature. And it is confes∣sed, that, as the notion of Fuga vacui, or that of the Airs pres∣sure, doth stand or fall as to this Experiment; so must it do as to the others also. I content my self therefore, to have shewed it in this; without expatiating to other particulars.FINIS.0