We took the former Syringe, and having ty'd a Weight, which weigh'd about two Pound and two Ounces, to the Sucker, we suspended it in our Receiver, the Orifice of the Barrel being first stopp'd with a Cork; and we observ'd, that after a few Exsuctions, the Weight drew down the Bar∣rel of the Syringe; and when the Air was again let in, the Pressure of it rais'd it up much faster than it fell.
But in this Experiment, it is to be noted, that if Air gets into the Barrel of the Sucker, whilst it is drawn down, it will not be rais'd quite so high again as before. And likewise, the Reason why it is requisite, that so large a Weight should be ty'd to draw it down, is because it must not only overpower the Pressure of the Air, but also the Straitness which requires a Force to make the Sucker move in the Barrel.
Secondly, it is observ'd, that as the Weight did not overpower the Pressure of the Air, till a good deal was exhausted; so neither did it rise again, till a sufficient Quantity of Air was let in again.