90 LANDS OF THE ARID REGION OF THE UNITED STATES. 
means has been steadily increasing during that time. In California and 
New Mexico irrigation has been practiced to a limited extent for a much 
longer time at the several Catholic missions under the old Spanish regime. 
In the history of the settlement of the several districts an important fact has 
been uniformly observed—in the first years of settlement the streams have 
steadily increased in volume. This fact has been observed alike in Cali- 
fornia, Utah, Colorado, and wherever irrigation has been practiced. As 
the chief development of this industry has been within the last fifteen years, 
it has been a fact especially observed during that time. An increase in the 
water supply, so universal of late years, has led to many conjectures and 
hypotheses as to its origin. It has generaliy been supposed to result from 
increased rainfall, and this increased rainfall now from this, now from that, 
condition of affairs. Many have attributed the change to the laying of 
railroad tracks and construction of telegraph lines; others to the cultivation 
of the soil, and not a few to the interposition of Divine Providence in 
behalf of the Latter Day Saints. 
If each physical cause was indeed a vera causa, their inability to pro- 
duce the results is quite manifest. A single railroad line has been built 
across the Arid Region from east to west, and a short north and south line 
has been constructed in Colorado, another in Utah, and several in California. 
But an exceedingly small portion of the country. where increase of water 
supply has been noticed has been reached by the railroads, and but a small 
fraction of one per cent. of the lands of the Arid Region have been 
redeemed by irrigation. This fully demonstrates their inadequacy. In 
what manner rainfall could be affected through the cultivation of the land, 
building of railroads, telegraph lines, ete., has not been shown. Of course 
such hypotheses obtain credence because of a lack of information relating 
to the laws which govern aqueous precipitation. The motions of the earth 
on its axis and about the sun; the unequal heating of the atmosphere, which 
decreases steadily from equator to poles; the great ocean currents and air 
currents; the distribution of land and water over the earth; the mountain 
systems—these are all grand conditions affecting the distribution of rainfall. 
Many minor conditions also prevail in topographic reliefs, and surfaces 
favorable to the absorption or reflection of the sun’s heat, etc., etc., affecting 
oe 
