1885.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 451 



five or more years, obtained, for the most part, from the office of the 

 Chief Signal Officer, United States Army : 



It is in the western counties of Texas where the rain is least, viz., 

 Tom Green, Crockett, Pecos, Presidio, El Paso, each larger than the 

 State of Vermont, that are found the worst lands of the State. In these 

 counties there are, outside of mountains, but two or three creeks per- 

 manently running, and only for 3 or 4 miles. 



There is no well-defined rainy season in Western Texas ; rain falls in 

 fitful " spells" at any, and often the most inopportune, time, with long 

 intervals of drought. Two or three months receive one-half of the yearly 

 precipitation. It is the season of sudden rises and floods which, in a 

 few hours, cause irreparable damages and again as promptly subside, 

 drained away by timberless arroyos, so that but a comparatively^ small 

 amount of moisture is retained in the earth and penetrates to the sub- 

 soil. 



Three or four, or more, months of the year are entirely without rain, 

 or only receive an insignificant amount. It is the season of dust storms 

 and prairie fires ; then springs dry up, streams stagnate or sink out of 

 sight. Even the liio Grande, above its main Mexican tributary, the 

 Conchas, ceases to run, and in many places its bed becomes a sinuous 

 avenue of glaring sand. 



Generally sjjeaking, there are two yearly waves of rainfall; the smaller 

 from April to June, the larger from August to November. They shift 

 more or less from year to year and vary also according to locality. 

 At San Antonio, a large proportion of the rain falls during the winter 

 and early spring. 



TEMPERATURE. 



Excluding the tropical southern half of Florida, the mean annual 

 temperature of the Lower Rio Grande is the highest in the United 

 States. Next to Key West (mean 77.5), Fort Ringgold has the unenvia- 

 ble distinction of being the hottest military post in the Union. Its mean 

 annual temperature (data from the office of the Chief Signal Officer) is 

 73.4, about a degree higher than that of Fort Yuma (72.3), the hottest 

 post west of the Rocky Mountains. Next to Ringgold, come in order : 



