SOME PECULIARITIES IN THE RAINFALL OF TEXAS. 63 
August rainfall, which is exceeded in quantity in the United 
States only along the south Atlantic and east Gulf coast, 
the monthly precipitation diminishes gradually to the west¬ 
ward and is almost nothing near the center of the barometric 
depression in the lower Colorado valley. In like manner it 
decreases to the eastward until it amounts to less than two 
inches over the immediate Cis-Pecos region. The lightest 
rainfall for August in Texas falls on this debatable ground, 
over which unfavorable meteorological conditions reduce to 
a minimum the chances of precipitation, whether drawn from 
the Gulf of Mexico to the southeast or the Gulf of California 
to the southwest. 
This condition of affairs is most favorable to western Texas, 
which would otherwise be an extremely arid region. The 
fact that the aqueous vapor around El Paso comes from the 
Gulf of California is also evidenced otherwise. In July the 
air along the coast of the Gulf of Mexico is charged with 
aqueous vapor to the extent of nine and a half grains on an 
average to each cubic foot of air. Following up the Bio 
Grande valley, the amount decreases from nine and four- 
tenths grains at Brownsville to about eight grains at Bio 
Grande City, seven grains at Eagle Pass, and six grains at 
the mouth of the Pecos. Up the Pecos valley the amount is 
only five and two-tenths grains at Fort Stockton, and to the 
westward seventy-five miles, at Fort Davis, as determined 
from three years’ observations, it is five and one-tenth. But 
on going much further from the Gulf of Mexico to El Paso, 
which is twelve hundred feet lower than Fort Davis, the 
amount rises to five, and nine-tenths grains. The much 
shorter distance from El Paso to the Gulf of California than 
to the Gulf of Mexico leads to the conclusion that the amount 
of aqueous vapor in the air during July to September also 
increases in the direction of the Pacific ocean. This conclu¬ 
sion is verified by the observations at Tucson, Arizona, where 
the mean for three years shows the following amounts of 
aqueous vapor in the air: July, 6.3 grains (0.4 grains more 
than at El Paso); August, the month of maximum rainfall, 
6.8 grains, and September, 4.8 grains. 
