March 30, 1906.] 



SCIENCE. 



501 



Professor M. W. Haskell: 'On collineations.' 



Professor G. A. Miller : ' Groups in which 

 every subgroup of composite order is invariant, 

 and a new chapter in trigonometry.' 



Professor G. A. Miller : ' The groups which 

 contain exactly thirteen operators of order 2.' 



The next meeting of the section will be 

 held at the University of California, on Sep- 

 tember 29, 1906. G. A. Miller, 



Secretary. 



THE SOCIETY OF GEOHYDROLOGISTS, VifASHINGTON. 



The fourth regular meeting of the society 

 was held on February Y, the following papers 

 being presented: 

 Decline of Artesian Head and Flows at Monte 



Vista and Denver, Colorado: 0. E. Sieben- 



THAL. 



At Monte Vista in the San Luis basin the 

 wells to the different aquifers show great uni- 

 formity of flow, although outside of the town 

 the wells to the same beds vary considerably 

 in head and discharge. There is, likewise, an 

 averaging of temperatures in the wells in 

 town. These inconsistencies are explained by 

 the mingling of the waters of the different 

 aquifers owing to faulty casing or the absence 

 of casing below the first flow. The flow and 

 head are both much less than when the wells 

 were first sunk. 



In the city of Denver there has been a sim- 

 ilar decline, the head having fallen from 80 

 or 90 feet above the surface in 1882-3 to 140 

 feet below the surface in 1904, with the pros- 

 pect of going still lower. The depression, 

 however, is local, as the wells in the Platte 

 Valley both north and south of the city still 

 flow. 



Warm Mineral Springs in the Bighorn Basin, 



Wyoming: C. A. Fisher. 



The Bighorn Basin in northwestern Wy- 

 oming is essentially a broad structural valley 

 formed between two large anticlinal folds, the 

 i Bighorn Mountains on the east and south and 

 the Rocky Mountain front range on the west. 

 Around the outer portion of the enclosed 

 valley there are a number of minor folds which 

 are roughly parallel to the larger uplift. 

 These folds are crossed in several places by 

 the larger streams draining the basin which 



have cut in them deep narrow canyons. In 

 these canyons or at their upper or lower ends 

 hot mineral springs occur which are usually at 

 or near the water level of the river. The 

 largest of these is in the southern part of the 

 basin near Thermopolis. It is situated about 

 thirty feet above the Bighorn River near the 

 axis of an anticline which exposes in its crest 

 upper carboniferous rocks. The water has a 

 temperature of 135° and the flow has been 

 variously estimated at from 1,000 to 2,000 

 gallons a minute. Hot springs of a similar 

 nature are found at the lower end of Shoshone 

 Canyon which crosses Rattlesnake Mountain 

 anticline in the northwest part of the basin. 

 The springs occur at the water level of the 

 Shoshone River and the temperature is 98°. 

 In the northeast part of the basin where the 

 Bighorn River crosses Sheep and Little Sheep 

 Mountain anticlines in Black and Sheep 

 canyons, respectively, a similar phenomenon is 

 observed. Here the springs occur in the 

 canyons at the level of the river. The water 

 is warm and somewhat mineralized. The 

 water of these springs, which is under artesian 

 pressure, is probably derived from some of the 

 deep-seated porous formations outcropping 

 high on the slopes of the surrounding moun- 

 tains. The high temperature of the water 

 may be caused either by its circulation in the 

 porous formations at great depth (not by 

 chemical action), or possibly by contact with 

 bodies of heated igneous rocks at considerable 

 depths. 



The fifth regular meeting of the society 

 was held on February 21, the following pro- 

 gram being presented : 

 Underground Water in the Vicinity of El 



Paso, Texas: G. B. Richardson. 



El Paso, Texas, which is the commercial 

 center of a large area in southwestern United 

 States and Mexico, is located in a region 

 where the annual rainfall is less than ten 

 inches and the water supply a fundamental 

 problem. The Rio Grande is the main asset, 

 although the flow of the stream is irregular. 

 The bed of the river has been dry foi* several 

 months at a time but during floods the flow is 

 enormous. Irrigation has been practised in 



