Mat 21, 1920] 



SCIENCE 



523 



berlin (T. C.) was led by his study of glacial cli- 

 mates to formulate several hypotheses which have 

 done much to advance geology (see "The Origin 

 of the Earth"). The recently published work of 

 Ellsworth Huntington concerning changes of cli- 

 mate is of notable interest to geologists. The data 

 he has accumulated and the stimulating hypotheses 

 he has advanced to interpret these data are worthy 

 of most serious consideration. The importance of 

 climate and the promised fruitfulness of its study 

 has led the speaker to attempt to facilitate its 

 study by summarizing what is known as to cli- 

 mate under the title "Laws of Climate." This 

 summary will be published soon in The Monthly 

 Weather Beview. 



A notable case of successive stream piracy in 

 southern Indiana: Clyde A. Malott. This paper 

 deals with the Knobstone cuesta region lying be- 

 tween the Muscatabook and Ohio Elvers near the 

 eastern margin of the driftless area of southern 

 Indiana. Its purpose is to show specifically the 

 responsibility of the geologic structure and topo- 

 graphic condition in drainage adjustment. Details 

 shown how the particular lithologic units with their 

 regional westward dip are important conditioning 

 factors in giving rise to topographic forms. Other 

 conditioning factors scarcely less important are 

 the so-called time factors, such as various uplifts, 

 rejuvenation and glaciation. The peculiarity of 

 the streams flowing east from the Knobstone es- 

 carpment is noted. Blue River with its peculiar 

 unchanging gradient is discussed in some detail, as 

 it is representative of all the streams on the back- 

 elope of the cuesta. It is shown that the piracy 

 of the Muddy Fork of Silver Creek has taken place 

 as a result of the geologic structure and topo- 

 graphic condition along the Knobstone cuesta. It 

 is not a single instance of piracy, but consists of 

 successive piracy Wherein a large number of tribu- 

 taries belonging to a single system have been an- 

 nexed one after another to the drainage system of 

 the invading stream. iSome 35 square miles have 

 been stolen. The conditions are highly favorable 

 for piracy to continue, and eventually the largest 

 part of the Muddy Fork of Blue Biver wiU be 

 taken over by the Muddy Fork of Silver Creek. 

 Such piracy will continue until a balanced condi- 

 tion of the gi'adients of the two stream systems ia 

 reached. Sutih a condition will mark the begin- 

 ning of old age of the stream systems, when 

 stream adjustments are practically complete. 



The Satsop formation and structure of the Cas- 

 cade range: J. Harlen Bketz. 



Geotectonic economy of thrust-faulting : Charles 

 B. Ketes. 



KoLLiN T. Chambekhn, 



Secretary 



THE AMERICAN MATHEMATICAL 

 SOCIETY 



The two (hundred and tenth regular meeting of 

 the society was held at Colmnlbia University on 

 Saturday, April 24, extending through the usual 

 morning and afternoon sessions. The total at- 

 tendance exceeded one hundred and thirty and in- 

 cluded eighty-two members. President Frank 

 Morley occupied the chair, yielding it to ex-Presi- 

 dent E. S. Woodward during the presentation of 

 the papers on relativity at the afternoon session. 

 The Council reported 'the election of the following 

 persons to membership in the Society: Professor 

 H. S. Everett, Bucknell University; Dr. J. L. 

 Eouse, University of Michigan; Professor Nilos 

 Sakellariou, University of Athens; Mr. H. L. 

 Smith, University of Wisconsin; Professor Eugene 

 Taylor, University of Wisconsin; Professor W. P. 

 Webber, University of Pittsburgh. Thirteen ap- 

 plications for membership were received. 



Professor L. P. Eisenhart was reelected to the 

 Editorial Committee of the Transactions, for a 

 term of three years. Professor P. F. Smith will 

 retire from the Editorial Committee on October 1, 

 after nine years' service as editor, and Professor 

 G. D. BirkhofE will fill out Professor Smith's nai- 

 explred term. Professor Oswald Veblen was ap- 

 pointed a represerutative of the society in the Di- 

 vision of Physical Sciences of the National 

 Research Council for a term of three years. Pro- 

 fessor Veblen 's Cambridge Colloquium lectures on 

 Analysis Situs vrill be published by the society in 

 the fall. Committees were appointed to confer 

 with a committee of the Mathematical Association 

 on joint plans for future meetings and to prepare 

 nominationB for officers for the annual election 

 next December. 



On the recommendation of the Council it was 

 unanimously vot«d to incorporate the society 

 under the membership corporations law of the 

 state of New York. The new f omi of organization 

 will involve hardly any changes beyond those nec- 

 essary to comply with legal requirements. The 

 board of trustees wiU be composed of those mem- 

 bers of the Council who are elected by the society, 

 the ex-oflieio members not being eligible as trus- 

 tees. Otherwise the constitution and by-laws, which 

 have come down from the beginnings of the s.o- 



