1be onely this, That the Air in the Recei
ver, being very much dilated, its Spring
muſt be very much weakn'd, and conſe
quently it can but faintly preſs up the
lower end of the ſtopple, whereas the
Spring of the external Air being no way
debilitated, he that a little lifts up the
ſtopple muſt with his hand ſupport a preſ
ſure equal to the diſproportion betwixt
the force of the internal expanded Air, and
that of the Atmoſphere incumbent upon
the upper part of the ſame key or ſtopple:
And ſo men being unuſ'd to finde any re
ſiſtance, in lifting things up, from the
free Air above them, they are forward to
conclude that that which depreſſes their
hands muſt needs be ſome weight, though
they know not where plac'd, drawing be
neath it.
ver, being very much dilated, its Spring
muſt be very much weakn'd, and conſe
quently it can but faintly preſs up the
lower end of the ſtopple, whereas the
Spring of the external Air being no way
debilitated, he that a little lifts up the
ſtopple muſt with his hand ſupport a preſ
ſure equal to the diſproportion betwixt
the force of the internal expanded Air, and
that of the Atmoſphere incumbent upon
the upper part of the ſame key or ſtopple:
And ſo men being unuſ'd to finde any re
ſiſtance, in lifting things up, from the
free Air above them, they are forward to
conclude that that which depreſſes their
hands muſt needs be ſome weight, though
they know not where plac'd, drawing be
neath it.
Experi
ment 2.
ment 2.
And that we have not miſ-aſſign'd the
cauſe of this Phænomenon ſeems evident
enough by this; That as Air is ſuffer
ed by little and little to get into the Re
ceiver, the weight that a man fancies his
hand ſupports is manifeſtly felt to decreaſe
more and more, the internal Air by this
recruit approaching more to an Æquili
brium with the external, till at length the
Receiver growing again full of Air, the
cauſe of this Phænomenon ſeems evident
enough by this; That as Air is ſuffer
ed by little and little to get into the Re
ceiver, the weight that a man fancies his
hand ſupports is manifeſtly felt to decreaſe
more and more, the internal Air by this
recruit approaching more to an Æquili
brium with the external, till at length the
Receiver growing again full of Air, the