rapid excursion to and fro of the drops may easily have caused
them to evaporate so fast as to freeze, and hence we may get hail.

While the cloud was electrified, it acted inductively on the earth
underneath, drawing up an opposite charge from all points, and thus
electrifying the atmosphere. When the discharge occurs this
atmospheric electrification engages with the earth, clearing the air
between, and driving the dust and germs on to all exposed surfaces. In
some such way also it may be that "thunder turns milk sour," and
exerts other putrefactive influences on the bodies which receive the
germs and dust from the air.

But we are now no longer on safe and thoroughly explored territory. I
have allowed myself to found upon a basis of experimental fact, a
superstructure of practical application to the explanation of the
phenomena of nature and to the uses of man. The basis seems to me
strong enough to bear most of the superstructure, but before being
sure it will be necessary actually to put the methods into operation
and to experiment on a very large scale. I hope to do this when I can
get to a suitable place of operation. Liverpool fogs are poor affairs,
and not worth clearing off. Manchester fogs are much better and more
frequent, but there is nothing to beat the real article as found in
London, and in London if possible I intend to rig up some large
machines and to see what happens. The underground railway also offers
its suffocating murkiness as a most tempting field for experiment, and
I wish I were able already to tell you the actual result instead of
being only in a position to indicate possibilities. Whether anything
comes of it practically or not, it is an instructive example of how
the smallest and most unpromising beginnings may, if only followed up
long enough, lead to suggestions for large practical application. When
we began the investigation into the dust-free spaces found above warm
bodies, we were not only without expectation, but without hope or idea
of any sort, that anything was likely to come of it; the phenomenon
itself possessed its own interest and charm.

And so it must ever be. The devotee of pure science never has
practical developments as his primary aim; often he not only does not
know, but does not in the least care whether his researches will ever
lead to any beneficial result. In some minds this passive ignoring of
the practical goes so far as to become active repulsion; so that some