AQUEOUS PHENOMENA OF THE PRAIRIES. 135 
noticed —the extent to which the water of the sloughs, or swales, 
reaches up the acclivities on either hand, even where the interval 
has a very considerable descent in the line of flow ; there is thus a 
broad concave bog that must strike a stranger with surprise, for it 
is not due to springs, but rather to a spongy retention of rainfall. 
Some peculiarities of prairie storms should not be omitted in 
this sketch. Nothing at the West is done by halves; when it 
rains, it rains; and the general surface is so uniform, the soil - 
to a certain depth so pervious, that something like a subterranean 
lake is suddenly formed, which rapidly rises, flooding cellars and 
even bursting up the cement of cellar floors by hydrostatic pres- 
sure, if cement-has been resorted to, by the trustful immigrant. 
One species of prairie storm should be elevated to the rank of a 
genus. It is mostly nocturnal in its habits and prowls all night ; 
its distinguishing characters are surges of rain, rhythmic roar of 
wind like that of heavy billows on a coast, incessant quiver of 
lightning, and overlapping continuous peals of thunder. It is as 
if the spirits of the old American Mediterranean sea were claiming 
again their last battle-ground—a suggestion harmonizing with the 
ocean-like level of the country and the looming mirages of sunny 
days. But the lightning of this species of storm seems to be 
among the clouds, and the new-comer soon becomes fearless ; in- 
deed, it does not require a long residence at the West to make 
one familiar with lightning, however timid he may have been at 
the East, although it remains true that thunder gusts are not 
pleasant to a person who is out on the open prairie, where man or 
horse is the only prominent object to attract the downward or up- 
ward bolts of electricity. Finally there is something peculiarly 
grand in western thunder. No hills break its smooth roll, and its 
long crescendos and diminuendos give a breath and cadence to 
the sound, as if chariots could be heard rolling on for hundreds 
of miles over the level prairie floors. 
The subjects of this article have not been in the path of the 
writer’s special study; but he believes that the prairie region 
offers a fresh and interesting field of observation in this regard. 
The reports and books where the information might properly be 
looked for, have failed to give him any information in respect to the 
relative humidity of the prairie atmosphere—a matter of prime 
importance. On average winter days, the writer found it from 
forty to fifty hundredths of saturation. 
