they known to the Anglo-Saxons, who, however, had adjectives of
direction in -AN or -EN, -ern and -weard, the last always meaning the
point TOWARDS which motion in supposed, the others that FROM which it
proceeds. The vocabulary of science has no specific name for one of the
most important phenomena in meteorology--I mean for watery vapor
condensed and rendered visible by cold. The Latins expressed this
condition of water by the word vapor. For INVISIBLE vapor they had no
name, because they did not know that it existed, and Van Helmont was
obliged to invent a word, gas, as a generic name for watery and other
fluids in the invisible state. The moderns have perverted the meaning of
the word vapor, and in science its use is confined to express water in
the gaseous and invisible state. When vapor in rendered visible by
condensation, we call it fog or mist--between which two words there is
no clearly established distinction--if it is lying on or near the
surface of the earth or of water; when it floats in the air we call it
cloud. But these words express the form and position of the humid
aggregation, not the condition of the water-globules which compose it.
The breath from our mouths, the steam from an engine, thrown out into
cold air, become visible, and consist of water in the same state as in
fog or cloud; but we do not apply those terms to these phenomena. It
would be an improvement in meteorological nomenclature to restore vapor
to its original meaning, and to employ a new word, such for example as
hydrogas, to explain the new scientific idea of water in the invisible
state.]

There is one branch of research which is of the utmost importance in
reference to these questions, but which, from the great difficulty of
direct observation upon it, has been less successfully studied than
almost any other problem of physical science. I refer to the proportions
between precipitation, superficial drainage, absorption, and