UNCERTAINTY OF MODERN METEOROLOGY. 25 
saturation of the subsoil, vary at comparatively short distances ; 
and though the precipitation upon very small geographical 
basins and the superficial flow from them may be estimated 
with an approach to precision, yet even here we have no present 
wneans of knowing how much of the water absorbed by the 
earth is restored to the atmosphere by evaporation, and how 
much carried off by infiltration or other modes of underground 
discharge. When, therefore, we attempt to use the phenomena 
observed on a few square or cubic yards of earth, as a basis of 
reasoning upon the meteorology of a province, it is evident that 
our data must be insufficient to warrant positive general con- 
clusions. In discussing the climatology of whole countries, or 
even of comparatively small local divisions, we may safely say 
that none can tell what percentage of the water they receive 
from the atmosphere is evaporated ; what absorbed by the ground 
and conveyed off by subterranean conduits; what carried down 
to the sea by superficial channels; what drawn from the earth 
or the air by a given extent of forest, of short pasture vegeta- 
-ern and -weard, the last always meaning the point towards which motion is 
supposed, the others that from which it proceeds. 
The vocabulary of science has no specific name for one of the most impor- 
tant phenomera 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 is rendered visible by condensation, we call it jog or nzst— 
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 clowd. 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 ydrogas, to ex- 
press the new scientific idea of water in the invisible state. 
