Physiologia Epicuro-Gassendo-Charltoniana, or, A fabrick of science natural, upon the hypothesis of atoms founded by Epicurus repaired [by] Petrus Gassendus ; augmented [by] Walter Charleton ...

SECT. V. The Fourth Capital Difficulty.

* 1.1WHy is the deflux of the Quicksilver alwayes stinted at the altitude of 27 digits, though in Tubes of different longitudes? when it seems more reasonable, that according to the encrease or enlargement of the Inanity in the upper part of the Tube, which holds proportion to the Longitude thereof; the Compression, and so the Resistence of the Aer circumpendent, ought also to be encreased proportionately: and consequently, that the Aequilibrium ought to be so much the higher in the Tube, by how much the greater Resistence the Aer makes without; because, by how much a larger Space is detracted from the Aer, by so much more diffused and profound must the subingression of its Atomical Particles be, and so the greater its resistence.

Solution.

* 1.2Certain it is, aswel upon the evidence of sense, as the conviction of seve∣ral demonstrations excogitated chiefly by Mersennus (in Phaenom▪ Hy∣draulic.) that a Cylindre of any Liquor doth with so much the more force or Gravity impend upon its Base, or bottom, by how much the higher its perpendicular reacheth, or, by how much the longer it is: and consequent∣ly, having obtained a vent, or liberty of Exsilition below at its Base, issues forth with so much the more rapidity of motion. And this secret reveals what we explore. For, according to the same scale of Proportions, we may warrantably conceive; that, by how much the higher the Cylindre of Quicksilver is in the Tube, by so much the more forcibly it impendeth upon its Base, in the Restagnant Quicksilver; and so having obtained a vent below, falleth with so much the more rapidity of motion or exsilition thereupon: and upon consequence, by so much the more violently is the incumbent Aer compressed by the restagnant Quicksilver ascending, its resistence overcome, and the subingression of its insensible particles into the inane Loculaments of the vicine aer, propagated or extended the far∣ther; and the space detracted from the Aggregate of Disseminate Inani∣ties, so much the larger, and consequently the Coacervate Vacuum appa∣rent in the superior region of the Tube, becomes so much the greater. And, because the Resistence made against the subingression, dilating or distend∣ing it self, is in the instant overcome, by reason of a greater impulse caused by the Cylindre of Mercury descending from a greater altitude; and that resistence remains,* 1.3 which could not be overcome, by the remnant of the Mercury in the Tube, at the height of 27 digits: therefore, is this Remain∣ing Degree of resistence, the manifest Cause, why the Mercury is Aequili∣brated here at the point of 27 digits, aswell when it falls from a high as a low perpendicular.

This may receive a degree of perspicuity more, from the transitory ob∣servation of those frequent Reciprocations of the Quicksilver, at the first

deflux of it into the restagnant, before it acquiesce and fix at the point of Aequiponderancy: no otherwise then a Ball bounds and rebounds many times upon a pavement, and is by successive subsultations uncessantly agi∣tated up and down, untill they gradually diminish and determine in a cessa∣tion or quiet. The Cause of which can be no other then this; that the extreme or remotest subingression of the insensible particles of the Aer, is (we confess) propagated somewhat farther, then the necessity of the Aequipondi••m requireth, by reason of a new access of Gravity in the Quick∣silver; but, instantly the insensible particles of the Aer, being so violently and beyond the rate of subingressibility prest upon, and made as it were more powerful by their necessary Reflexion, then the re••idue of Quicksil∣ver remaining in the Tube; result back to their former station of liberty, with that vehemency, as they not only praevent any further subingression, and reduce the even-now-superior and conquering force of the Quicksilver to an equality; but also repell the Quicksilver delapsed up again into the Tube above the point of the Aequipondium: and again, when the Quick∣silver defluxeth, but not from so great an altitude, as at first; then is the Aer again compelled to double her files in a countermarch, and recede from the restagnant Quicksilver, though not so far, as at first charge. And thus the force of each being by reciprocal conquests gradually decreased, they come to that Equality, as that the Quicksilver subsists in that point of altitude, wherein the A••quilibrium is.

Notes

• * 1.1

  Art. 1. The Fourth Capital Diffi∣culty propo∣sed.
• * 1.2

  Art. 2. The full solu∣tion thereof, by demonstra∣tion.
• * 1.3

  Art. 3. The same con∣firmed, by the theory of the Cause of the Mercuries fre∣quent Recipro∣cations, before it acquiesce at the point of Aequipondi∣um.