August 10, 1906.] 



SCIENCE. 



181 



and the results, if they are not due to some 

 obscure barometric effect which has escaped 

 me, are most directly referable to changes of 

 pressure within the atmosphere, the number 

 of the colloidal nuclei specified being greatest 

 when the pressure is least. This view, more- 

 over, would not be incompatible with the per- 

 sistence of terminal coronas referred to above. 

 It is also compatible with the following. If 

 among the initial nuclei entrapped ( which lie 

 very near the region of ions) the ions actually 

 preponderate, the observations would then 

 mean that increased ionization accompanies 

 the falling barometer. Under these condi- 

 tions, however, radioactive emanation is known 

 to be withdrawn from the stagnant air within 

 the porous ground and the earth generally. 

 Hence the data could now be interpreted as 

 evidence of the necessary fluctuation of such 

 emanation with the barometer. 



I may add that I have since installed a 

 second apparatus side by side with the first 

 and that the data, though differing in their 

 details, show the same dependence on the 

 barometer in their broader time variations. 



Carl Barus. 



Bkown University. 



USE OP THE TERM PERMIAN IN AMERICAN GEOLOGY. 



For over fifty years the Permian question 

 has been one of the moot problems of Amer- 

 ican geology. Of late it has been quite gen- 

 erally agreed that the title should not, at 

 least, be applied to any American formation 

 having the taxonomic rank of period or sys- 

 tem, coordinate with such terms as Carbonifer- 

 ous or Cretaceous. 



Division is now upon the point whether 

 the so-called Permian section as represented 

 in Kansas should be called by Murchison's 

 title and given the rank of series, or whether 

 the name should not be abandoned altogether 

 as a designation for any American formation. 



Upon this point Professor Prosser has re- 

 cently made a summary of opinion. Among 

 the statements is this : " There is still a dif- 

 ference of opinion among American geologists 

 in regard to the correlation of the Upper 

 Paleozoic formations of Kansas with the Rus- 

 sian Permian. The Journal of Geology, pub- 



lished in 1898 '■ A Symposium on the Classifi- 

 cation and Nomenclature of Geologic Time- 

 divisions,' in which Dr. Williston, Professor 

 Calvin and Dr. Keyes reported adversely both 

 as to the identification of the Permian in 

 Kansas and as to its recognition as a period co- 

 ordinate with the Carboniferous or Devonian; 

 while Dr. William B. Clark stated that for the 

 later divisions of the Paleozoic he should em- 

 ploy the chronologic terms Carboniferous and 

 Permian." 



Professor Prosser further observes : " No 

 one has, perhaps, insisted as strenuously as 

 Dr. Keyes that the name Permian should be 

 dropped from American geology. In 1897 he 

 attended the sessions of the International 

 Congress of Geologists at St. Petersburg and 

 participated in the excursions to the Carboni- 

 ferous and typical Permian of Russia. Later 

 he prepared a paper on the ' American Homo- 

 taxial Equivalents of the Original Permian,' 

 and quotations from this can not be regarded 

 as from one favoring the retention of the 

 name ' Permian.' " 



It is quite manifest that Professor Prosser 

 has objected to my usage of the title of 

 ' Oklahoman series ' for the so-called Lower 

 Permian of Kansas. My repeated use of the 

 term Oklahoman has been made advisedly. It 

 had been thought quite desirable to have the 

 title of this section distinctive, irrespective 

 of what age might be eventually assigned to it. 



The recent discovery in New Mexico and 

 Texas of a great formation (Guadalupan 

 series) having a thickness of more than 2,500 

 feet, that appears to be intercalated between 

 the Carboniferous Red Beds (Cimarronian 

 series) and the equivalent of the Oklahoman 

 series, indicates that the Kansas section of the 

 latest part of the Paleozoic is not nearly so 

 complete as it was thought to be. It also sug- 

 gests that in Kansas there are no formations 

 below the Red Beds that can be considered of 

 late Carboniferous age, or that might be 

 paralleled with the Permian at all. This, it 

 would seem, would almost put an end to the 

 contention for a Permian age of such Kansas 

 beds as the Neosho, Chase and Marion forma- 

 tions. 



Tschemychew, who is one of the best au- 



