550 



SCIENCE 



[N. S. Vol. XXXIII. No. i 



there will mean a thickness radially of only per- 

 haps one hundred kilometers, which implies an 

 indistinctness of outline of less than a half second 

 of arc, which is not discernible. In consequence 

 of the deeper source of the observed radiation the 

 effective temperature of the source at the center 

 of the sun's disc exceeds that at the sun's edge. 

 Hence the intensity of the radiation falls off from 

 the center to the edge. The diminution of the 

 effective temperature of the source affects short 

 wave rays more powerfully than longer ones, hence 

 the contrast between edge and center is greater 

 for 'violet than for red, as long known. The gran- 

 ulation of the sun 's disc the speaker regarded as 

 evidence of slight differences of temperature from 

 place to place, with attending differences of radi- 

 ation. He called attention to the fact that such 

 differences of brightness appear most strongly in 

 spectroheliographic photographs with the red hy- 

 drogen line, where of course it is out of the ques- 

 tion that the effect is due to the precipitation of 

 a cloud. But it is stated by some that the juxta- 

 position of the gases to empty space must neces- 

 sarily cause a precipitation of a cloud by cooling. 

 The speaker drew attention to the existence of 

 water vapor without clouds in many regions of 

 the earth 's atmosphere, and to the existence of 

 steam without a cloud for some distance above the 

 stack of a locomotive. The question of cloudy 

 precipitation depends upon the rate of supply of 

 heat to take the place of energy radiated away, 

 and on the rate of change of density of the gas at 

 the boundary. A cloud is not a necessity. Many 

 other points were discussed. 



(The foregoing abstracts are by the respective 

 authors of the papers.) 



E. L. Fakis, 

 Secretary 



THE GEOLOGICAL SOCIETY OP WASHINGTON 



At the 238th meeting of the society, held at the 

 Cosmos Club on Wednesday evening, January 25, 

 1911, under informal communications, IVIr. C. W. 

 Hayes exhibited a series of specimens illustrating 

 the growth of concretions of different composition 

 under a variety of conditions. 



(o) Calcite concretions from the famous Dos 

 Bocas oil well, south of Tampico, Mexico. This 

 well now forms a great caldron about 36 acres in 

 extent. The ebullition due to the escape of gas, 

 which a year ago was continuous, is now intermit- 

 tent, having a period of about two hours. The 

 well still yields a large quantity of hot (160° F.) 



salt water heavily charged with lime and a small 

 amount of heavy oil in the form of a frothy emul- 

 sion. The water deposits lime carbonate partly in 

 concretionary form. The concretions, from .5 to 

 1.5 inches in diameter, being kept in motion by 

 the ebullition in the caldron are almost perfect 

 spheres, made up of very thin concentric layers. 



(b) Bauxite concretions from the Rome district 

 in northwest Georgia. The formation of these 

 deposits has been ascribed to hot-spring action and 

 the conditions during their deposition were prob- 

 ably analogous to those seen in the Dos Bocas well. 

 Instead, however, of being charged with lime in 

 solution, the water contained aluminum hydroxide 

 in suspension and this was deposited in concentric 

 layers forming the bauxite concretions. 



(c) Calcite concretions from San Antonio, Tex. 

 These occur in great abundance in the ' ' telpe- 

 tate" or "caliche," a widespread chalky lime- 

 stone formation, produced at or near the surface in 

 semi-arid limestone regions by the ascent of water 

 through capillary action and evaporation with 

 deposition of the dissolved salts. Ordinarily the 

 deposit has a platy structure, but in places, as at 

 San Antonio, it is strongly concretionary. 



{d) Bauxite concretions from the Little Eock 

 district, Ark. These deposits are similar in form 

 and possibly analogous in origin to the telpetate 

 of San Antonio. The concretions are nearly indis- 

 tinguishable from those of San Antonio, although 

 entirely different in composition. 



Regular Frogram 

 The Topograpliic Development of the Catskill 



Mountains: H. E. Meev^in. 



The Catskill Mountains and the adjacent region 

 have the structure of a coastal plain with a very 

 resistant thick member at the top. The Hudson- 

 Mohawk valley developed as a subsequent valley 

 in the weaker lower member that outcropped along 

 the borders of the Adirondack-Taconic old land. 

 The Hudson became superposed upon the complex 

 structure of the Highlands which were buried be- 

 neath the coastal plain series. This river seems 

 to have had its course well established by the 

 close of the Paleozoic so that it was antecedent 

 to the folded structure beneath and east of the 

 Catskills. 



The topography of the northeastern Catskills, 

 though originally of the peak-and-spur type char- 

 acteristic of mature plateaus, is now strongly 

 influenced by the southward dip of the rocks. The 

 drainage of this part of the Catskills was origi- 

 nally westward through the Delaware and Susque- 



