IRRIGATION. 701 



namental stones; not less the siliceous conglomerations from the foot of the 

 Comanche Mountains, which conglomerations resemble mosaic work, are very 

 hard, and take a beautiful polish. 



Up to this time I have found no fire or honey opals, but comparing the 

 matrix in which opals are found in Mexico and Hungary with some of our 

 metamorphic West Texas rock, and considering the conditions under which 

 the metamorphoses probably took place, it may be only a matter of time and 

 careful prospecting to find opals also in West Texas. 



We may also predict that the fine-grained and multi-colored marbles known 

 as Mexican onyx, which since a short time have also been mined in New 

 Mexico and converted into ornamental and art works, will be found and 

 worked in West Texas, and that even the massy dark green and brown ser- 

 pentines will be by and by utilized. 



IRRIGATION. 



It is not so much the want of rain as the lack of rainfall in the season 

 when it is needed that makes irrigation the prime condition for the utiliza- 

 tion of these flats and for the raising of agricultural and horticultural pro- 

 ducts. 



The average rainfall for the period between 1879 and 1889 amounted to 

 about twenty inches (19.9) at the observation station at Fort Davis annually, 

 and about thirteen inches for the station at Fort Bliss. There is no doubt 

 that the observations for the stations are correct, but the peculiar meteoro- 

 logical conditions of West Texas will not allow one to make conclusions as 

 to the general average rainfall from the observations of two or three stations 

 located about two hundred miles from each other. The observations made 

 in Fort Davis and Fort Bliss (El Paso) are correct and hold good for the 

 immediate neighborhood, but not for the country ten or fifteen miles off. 

 During the months of September and October last year I measured eleven 

 and five-sixteenths inches of rain in one camp at the foot of the Quitman 

 Mountains; during the same time in Sierra Blanca Junction, about seven 

 miles east of this camp, the rainfall hardly amounted to two inches; and 

 about six miles southeast of this place the rainfall was heavier than at the 

 camp. General rains spreading over large areas are hardly ever observed, 

 and if so they very seldom last over twenty-four hours. The rains come 

 mostly down in heavy showers, particularly along the mountain slopes, and 

 the water runs off as quickly as it pours down, and not even a superficial ob- 

 server will fail to mark that the average rainfall is higher than the average 

 of the two observation stations. 



But taking the average rainfall observed at Fort Davis (19.9) with that at 



