Experimental philosophy, in three books containing new experiments microscopical, mercurial, magnetical : with some deductions, and probable hypotheses, raised from them, in avouchment and illustration of the now famous atomical hypothesis / by Henry Power ...

Experiment 15. Of Auzotius.

TAke a long Tube, with a Head like a Weather-Glass, onely open at both ends, as A B, and with a Circular ledge at B (to tye a Bladder about) as also a little pipe G, which opens into the Head thereof, re∣verse it, and into the mouth of the Head let down a hol∣low Cube of wood or Ivory C, as large as the Head will contain; which with its four corners may rest upon the neck of the Glass (as in the Second Figure:) then take a small Cylinder of Glass, of above 28. inches, and set it in the middle of the Cube C, and close the mouth of the Head B, and the pipe G with Bladders, so that no Ayr can get in; then stopping the Orifice of the long Tube A, with your thumb, let another tunnel-in Mercury at the top of the small Glass-tube F, which will first fill the Cube C, and then running over, and falling down the Interstices, that the four Angles of the Cube C makes with the neck of the Glass, shall at last come to fill both Tubes: Lastly, closing the Orifice of the great Tube A into the Vessel'd Quicksilver, and there withdrawing your finger, as in the former Experiments, you shall see all the Quicksilver in the small Tube F B, to fall into the Cubical Vessel C, (which being not able to contain it) it, together with all the Quicksilver, in the head and neck of the great Glass-tube, will come down to its wonted pitch E 29. inches of that in the Vessel.

Which shews, the descending Quicksilver perpetual∣ly observes its Sandard-altitude from what height soe∣ver. But the great business is, If you open the little pipe G, and let in any Ayr, you shall not onely see it to

depel the Mercurial Cylinder A E, but to force up the Quicksilver out of the Cube C, into the small Tube B F, to its wonted Altitude of 29. inches, and totally to expel the Mercurial Cylinder E A out of the Tube: which ocularly demonstrates, that it is the At∣mosphaerical Ayr that (in the first Experiment) raises and keeps up that Cylinder of Quicksilver in the Tube of 29. inches in Altitude, or thereabouts.