lation of prognostics concerning rain, wind
and storm, and there investigation ceased for ages. For nearly two
thousand years the citizens of the world rose every morning to rejoice
in fair weather or be wet by showers, to see their crops destroyed
by frost or their ships by winds, and never made a single attempt to
discover any scientific reason or rules in the matter--apparently
did not suspect that there was any cause or effect behind these daily
occurrences. They accounted for wind or rain as our grandfathers did
for a sudden death, by the "visitation of God." In fact, Nature--which
is the expression of Law most inexorable and minute--was the very last
place where mankind looked to find law at all.

About two hundred and thirty years ago Torricelli discovered that
the atmosphere, the space surrounding the earth, which seemed more
intangible than a dream, had weight and substance, and invented the
barometer, the tiny tube and drop of mercury by which it could be
seized and held and weighed as accurately as a pound of lead. As soon
as this invisible air was proved to be matter, the whole force of
scientific inquiry was directed toward it. The thermometer, by which
its heat or cold could be measured--the hygrometer, which weighed,
literally by a hair, its moisture or dryness--were the results of the
research of comparatively a few years. Somewhat later came the curious
instrument which measures its velocity. As soon as it was thus made
practicable for any intelligent observer to handle, weigh and test
every quality of the air, it became evident that wind and storm, even
the terrible cyclone, were not irresponsible forces, carrying health
or death to and fro where they listed, but the result of plain,
immutable; laws. It was an American in this our Quaker City who
reduced the wind to a commonplace effect of a most ordinary cause.
Franklin, one winter's day passing with a lighted candle out of a warm
room into a cold one, saw that as he held it above his head the flame
was blown outward before him: when he held it near the floor, the
flame was blown into the room. The shrewd observer stood in the
doorway, instead of hurrying out, as most of us would have done,
to save the wasting candle. The warm air in the heated room, he
conjectured, was expanded by the heat, consequently it rose as high as
it could, and made a way for itself out of the room at the upper part
of the doorway, while the heavier cold air from without rush