E. MINERALOGY AND GEOLOGY. 219 



E. MINERALOGY AND GEOLOGY. 



STRUCTURE OF THE EARTH. 



An elaborate paper, presented by General Barnard to the 

 Smithsonian Institution, on the internal structure of the 

 earth, deduces the following conclusions : That, whereas the 

 analysis of Professor Hopkins seems to establish that the ro- 

 tation of the solid crust imparts to the fluid nucleus a motion 

 nearly, if not quite, as rapid as its own, and the fluid thereby 

 acquires a proper rigidity, by which it reacts upon the shell 

 as if it were a solid mass, this pressure tends to preserve the 

 earth's nutation and precession unchanged. If the fluid be 

 heterogeneous, the same rigidity is attained, and the power- 

 ful pressure that would be exerted upon the thin, rigid shell 

 would probably produce no noticeable changes; while, if the 

 shell be not of a rigidity far surpassing that of the known 

 constituents of the crust, the precessional motion of the earth 

 would, owing to the neutralizing effect of tidal protuberances, 

 be scarcely observable. Proc. Am. Assoc, inN.Y. Trib.,1873. 



NATIVE TELLURIUM IN COLORADO. 



One of the most interesting results of the examination of 

 sundry minerals collected during the geological survey of 

 Professor Hayden, in 1873, according to Dr. F. M. Endlich, 

 one of the geologists of the expedition, consists in the fact 

 that native tellurium was found among some of the tellurides 

 from the Red Cloud Mine at Gold Hill, Colorado. It oc- 

 curred in a specimen weighing about six pounds, a me- 

 chanical mixture of quartz and native tellurium in equal pro- 

 portions. Except in Transylvania, tellurium has never been 

 found in its native state. Small' admixtures of bismuth, se- 

 lenium, iron, gold, and silver are associated with it, so that 

 the tellurium is only about ninety-one per cent, of the mineral. 



THE MOLECULAR STRUCTURE OF METEORIC IRON. 



Dr. J. Lawrence Smith, of Louisville, Kentucky, in a recent 

 article on the meteor of Howard County, Indiana, states that 

 his own conviction is that we shall not arrive at a satisfac 



