Observations touching the principles of natural motions, and especially touching rarefaction & condensation together with a reply to certain remarks touching the gravitation of fluids / by the author of Difficiles nugae.

REMARK XXXII, XXXIII.

IN these two Remarks the Remarker endeavours to shew,

1. The Groundlessness of the Solu∣tion offered by me to the Torricellian Phaenomena. And, 2. Its Repug∣nancy.

The former he saith he hath shewn in Remark 32. But all that is done to shew it, is to substitute certain inevi∣dent, and I think, mistaken Supposi∣tions: As,

1. The perviousness of Glass to the subtiler aerial particles; this indeed he hath often said, but no where pro∣ved; and if it were admitted, would not only perfectly destroy the appa∣rent Phaenomena in that Instrument, but would utterly confound his Answer to the resiliency of the Mercury upon a sudden lifting up and separation of the Tube from the restagnant Mercu∣ry: For what need such a violent

resilition where the top of the Tube admits the subtiler aerial particles to pervade the Glass?

2. The gentle inclining of the Tube to prevent the tumultuary agi∣tation of the Mercury. But what I have shewn in my Observation upon Remark 17, &c. I think sufficiently discovers the impotence of this Ob∣jection.

3. The gravitation upward by a Circle of motion, is utterly unapt to salve the resilition; for that circulation can be but a slow, gentle motion, and cannot possibly have so rapid a motion by the imaginary straightness of the Channel; as we may suppose in the Streights in the Sea; upon which the Ocean presseth; but this neither can nor need receive a greater portion of subtil Air to relieve it than possibly 2 inches in height, and the 8^th part of an inch in Diameter, where the amplitude of the Tube is no grea∣ter.

As to the Second, namely, the re∣pugnancy which is assigned.

1. In that I deny a Vacuum, which he saith cannot be by another way pre∣vented, but by the transition of the subtil particles of Air through the Glass; but such a course of argumen∣tation seems to be of kin to that which is called Petitio Principii, he knows I assign another cause, though he di∣spute the truth of it. Then he pro∣ceeds to the leisurely inclining of the Tube; which I confess is often repeat∣ed, but I think need not be more than once answered, which I think is done in my Observations upon Remark 17, &c.

Then he proceeds to the Argument touching Rarefaction, and the incon∣venience of the penetration of dimen∣sions, and so endeavours to prove re∣pugnancies in what is said by a Problem that deserves more discussion than the Argument in hand, as hath been shew∣ed in the beginning of this Book, wherein I have nevertheless expressed my thoughts touching it.

I cannot tell what the Remarker imagines or conceives against the co∣hesion

of grosser Bodies by the tension of lighter bodies, but I can tell what is evident to my sense, and so may any that will give his Senses leave freely to determin, without stifling them by Notions, namely, that there is as plain a cohesion in the Magdeburgh Hemi∣spheres; yea, and in the Torricellian Engin, as there is between things fast∣ned each to other by a string: And therefore I cannot so over-readily change the conviction of my Senses, for a Notion or Conception asserted and magnified, but not proved.

But to infer that because Water, which is above 900 times crasser than Air, is not compressible to a sensible smaller room by a great weight, there∣fore a portion of subtil Matter cannot be extracted out of it or Mercury, with so small a weight as the Mercurial Cylinder, or that the effluvia of Water or Mercury, which are as subtil as Air, cannot be expanded by a less weight than Water compressed into a sensible narrower room, seem hard il∣lations, and very inconsequential; for

we see the heat of a mans hand will expand Air in Weather-Glasses to near a double extension.