One can imagine the feeling with which
Torricelli removed his thumb, and the delight he experienced on
finding that his thought had forestalled a fact never before revealed
to human eyes. The column sank, but it ceased to sink at a height of
thirty inches, leaving the Torricellian vacuum over-head. From that
hour the theory of the pump was established.

The celebrated Pascal followed Torricelli with another deduction. He
reasoned thus: If the mercurial column be supported by the atmosphere,
the higher we ascend in the air, the lower the column ought to sink,
for the less will be the weight of the air overhead. He caused a
friend to ascend the Puy de Dome, carrying with him a barometric
column; and it was found that during the ascent the column sank, and
that during the subsequent descent the column rose.

Between the time here referred to and the present, millions of
experiments have been made upon this subject. Every village pump is
an apparatus for such experiments. In thousands of instances,
moreover, pumps have refused to work; but on examination it has
infallibly been found that the well was dry, that the pump required
priming, or that some other defect in the apparatus accounted for the
anomalous action. In every case of the kind the skill of the
pump-maker has been found to be the true remedy. In no case has the
pressure of the atmosphere ceased; constancy, as regards the lifting
of pump-water, has been hitherto the demonstrated rule of nature. So
also as regards Pascal's experiment. His experience has been the
universal experience ever since. Men have climbed mountains, and gone
up in balloons; but no deviation from Pascal's result has ever been
observed. Barometers, like pumps, have refused to act; but instead of
indicating any suspension of the operations of nature, or any
interference on the part of its Author with atmospheric pressure,
examination has in every instance fixed the anomaly upon the
instruments themselves. It is this welding, then, of rigid logic to
verifying fact that Mr. Mozley refers to an 'unreasoning impulse.'

Let us now briefly consider the case of Newton. Before his time men
had occupied themselves with the problem of the solar system. Kepler
had deduced, from a vast mass of observations, those general
expressions of planetary motion known as 'Kepler's laws.' It had been
observed that a magnet attracts iron; and by one of those flashes of
inspiration which reveal to the