, 1874-01-03

The presence of stately ruins in solitary
deserts is conclusive proof that climatic
changes have taken place within the period
of human history in many Eastern coun-
tries once highly cultivated and densely
peopled, but now an arid waste. AL
though the records of geology teach that
great vicissitudes of climate, from the
torrid conditions of the coal period to
those which produced the glaciers of the
Drift, may have in turn occurred in the
same region, we have no reason to believe
that any material changes have been
brought about by astronomical rather
than natural causes within the historical
period. We cannot account for the
changes that have occurred in these sun
burnt and sterile plains where these ira
ces Of mans first civilization are found,
once clothed with q l~uxurian vegetation,
except by ascribing their present condition
to the improuadent acts Of man IN destroying
the trees and plants which omce clothed the
surface and sheltered 1t from the sun and the
aDinds. As this shelter was removed the
desert approached, gaining new power as
it's area increased, until it swept over vast
regions once popuIous and fertile, and left
only the ruins OF former magni6cencp. In
more temperate climates the effect is less
striking, yet it is sufficiently apparent
everywhere, and throughout our whole
country, and especially IN the hills once
wooded. and in the level and swampy re-
glons of the Eastern and Northern States.
The failure Of springs and wells, the dry
1pw ,1n of h.ooLc x,bSoL1 .~-l:-l
ample hydraulic power through the Sum
mer and the increasing difficulty of Sc
curing water for canal navigation and
wholesome water for cities, are becoming
every day something more than a subject
of casual remark. They are destined to
become a theme of careful scientific and
practical inquiry 10 ascr5 ain how these
growing evils maybe cAeeked, and how
the lost advantages may be regained. We
regard the ocean itself as the source
whence the moisture precipitated in rains
is mainly derived. It's area changes not.
The exposure to solar heat is uniform,
and except as varying within fixed limits
by the revolution of the earth's axis in it's
revolution around the sun, there are no as
Economical or other causes that should sem
sibly change the annual amount of general
evaporation from the surface Of the ocean
from year to year or from age to age. The
vapors raised from the sea are distributed
by the winds over the land, and descend
as rain where mountain ranges, forests,
and other causes favor condensation. 1t
Is probable that the Gulf of Mexico fur
nishes more vapor for rain than the Allan
tic Ocean flor the United States, of
c~ourse), its influence being felt through
out and beyond the great basin of the
Mississippi and its tributaries.
THE CAUSES Or DRoUTH AND FLOOD
In 4 work which / recently prepared
for the regents Of the University of the
State Of NeW-Yofk. I was able to collect
from al sources and from various periods
in some stations for almost half.a CEN
tury-about 1000 years OF rainfall re-
cords. within the State Of New York, and
in = volume published within the last
year BY the Smithsonian Institution there
is = much more extended series for the
whole country. These extensive series
are not enough to determine with any
ahow of occ0racy the secuiar changes, if
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