Geology and Mineralogy. 485 



to believe that the increase in the spectrum was toward the more 

 refrangible end. H. F. Weber, from observations on incandescent 

 electric lights, has discovered that bodies begin to glow at a 

 much lower temperature than the limit set by Draper. 



The first trace of light was seen at about 390°, and was of a 

 spectral gray color. As the temperature increased, the spectrum 

 of the glowing carbon filament did not increase more rapidly 

 toward the violet than toward the red ; but increased equally in 

 both directions. The first rays which are perceived by the eye 

 come from the part of the spectrum which sends forth the maxi- 

 mum energy when the filament is heated to its highest point* 

 The experiments were repeated with metallic filaments raised in 

 temperature by non-electrical methods, and the results obtained 

 by electrical currents were thus confirmed. Weber maintains 

 also that all bodies do not begin to glow at the same temperature, 

 as the results of Dr. Draper seemed to show. A plate of plati- 

 num began to send forth gray light at 391°; while a gold plate 

 showed the same character of light at 417°. In another experi- 

 ment, a platinum plate began to glow at 396°, and an iron 

 plate at 378°. The paper of Weber is followed in the Anna- 

 len der PhysiTc by one on the same subject by Fr. Stenger, who 

 confirms in general the results of Weber ; but suggests that the 

 varying sensitiveness of the observer's eye to various colors and 

 to their degrees of intensity may play an important role in the 

 determination of the relative rate of increase of the spectrum of 

 glowing bodies. — Ann. der Physik und Chemie, No. 10, 1887., 

 pp. 256-275. j. t. 



II. Geology and Minekalogy. 



1. On the Location of some Vertebrate Fossil Beds in Hondu- 

 ras, C. A.; by Fkank L. Nason. — The locality referred to is sit- 

 uated about twenty-seven miles east of the Ulna river and in the 

 ISIigi'ito valley. This valley is bounded on the east and west by 

 ranges of lofty mountains varying in height from three to six 

 thousand feet. The mountains gradually draw together north 

 and south, enclosing a basin from forty to fifty miles in length and 

 about twelve in width. From the northern extremity of the val- 

 ley two streams (one of them the Rio Roman), join to form the 

 Rio Comayagua, which empties, later, into the Ulna, thus forming 

 the outlet or drainage for the valley. 



At the foot of the mountains are ranges of foot-hills not over 

 one thousand feet in height. These foot-hills are evidently the 

 debris washed from the mountains and into the lake which at 

 that time filled the valley. A rather striking feature of these 

 foot-hills, as well as of the valley, is the almost entire absence of 

 tropical vegetation. While the mountains are clothed with the 

 customary tangled growth, these hills and the valley have only 

 straggling thickets of guava and other shrubs, though quite a 

 dense growth of grass is abundant which furnishes pasturage 



