or by shaking the Glass, the whole Mercury falls down to the height of
29 or 30 Inches.
And of the same kind with these Experiments are those that follow. If
two plane polish'd Plates of Glass (suppose two pieces of a polish'd
Looking-glass) be laid together, so that their sides be parallel and at
a very small distance from one another, and then their lower edges be
dipped into Water, the Water will rise up between them. And the less
the distance of the Glasses is, the greater will be the height to which
the Water will rise. If the distance be about the hundredth part of an
Inch, the Water will rise to the height of about an Inch; and if the
distance be greater or less in any Proportion, the height will be
reciprocally proportional to the distance very nearly. For the
attractive Force of the Glasses is the same, whether the distance
between them be greater or less; and the weight of the Water drawn up is
the same, if the height of it be reciprocally proportional to the
distance of the Glasses. And in like manner, Water ascends between two
Marbles polish'd plane, when their polish'd sides are parallel, and at a
very little distance from one another, And if slender Pipes of Glass be
dipped at one end into stagnating Water, the Water will rise up within
the Pipe, and the height to which it rises will be reciprocally
proportional to the Diameter of the Cavity of the Pipe, and will equal
the height to which it rises between two Planes of Glass, if the
Semi-diameter of the Cavity of the Pipe be equal to the distance between
the Planes, or thereabouts. And these Experiments succeed after the same
manner _in vacuo_ as in the open Air, (as hath been tried before the
Royal Society,) and therefore are not influenced by the Weight or
Pressure of the Atmosphere.
And if a large Pipe of Glass be filled with sifted Ashes well pressed
together in the Glass, and one end of the Pipe be dipped into stagnating
Water, the Water will rise up slowly in the Ashes, so as in the space
of a Week or Fortnight to reach up within the Glass, to the height of 30
or 40 Inches above the stagnating Water. And the Water rises up to this
height by the Action only of those Particles of the Ashes which are upon
the Surface of the elevated Water; the Particles which are within the
Water, attracting or repelling it as much downwards as upwards. And
therefore the Action of the Particles is very strong. But the Particles
of the Ashes being not so dense and close together as those of Glass,
their Action is not so strong as that of Glass, which keeps Quick-silver
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