6 Bulletin Wisconsin Natural History Society. [Vol. 7, Nos. 1-2. 



approved. The secretary read an invitation extended by Milwaukee- 

 Downer College to the society, asking- its members to attend the com- 

 memoration of the 100th anniversary of the birth of Charles Darwin, 

 on Friday evening, February 5, at which Dean Edward A. Birge of the 

 University of Wisconsin, was to deliver an address. 



The names of Miss Flora Elmer, Miss Delia S. Guile, Miss Anna M. 

 Berger, Mrs. Sarah M. Boyd, and Messrs. William George Thwaits, 

 Herman F. Haessler, N. A. Christensen, Kudolph M. Koss, Adolph Fink- 

 ler, Samuel D. Adler, Dr. Joseph Schneider, Richard E. W. Sommer. 

 Eltinge Elmore, William W. Plankinton, William W. Allis, Louis W. 

 Bunde, Dr. A. J. M. Lasche, Dr. J. S. Bachelor, George B. Terry and 

 F. A. W. Kieckhefer were proposed for membership and subsequently 

 elected by the board of dirctors. 



Professor E. C. Case then lectured on "Earthquakes, Their Causes 

 and Results." Dr. Case described the various sorts of earth tremors, or 

 seisms, showing graphically the different types of motion by means of 

 photographs of objects in regions that had been visited by earthquakes. 

 Many cases were described in detail, after which he passed to a con- 

 sideration of the causes of earthquakes, stopping to call attention to 

 the popular fallacy that earthquakes and volcanic eruptions are due to 

 the same causes. He told of the old centrum theory of earthquakes 

 which had held that they were due to explosions or disturbances at 

 special points beneath the solid crust. This view was at one time 

 widely accepted, but has now been cast aside as it does not accord 

 with observed facts. The more recent idea that earth tremors are due 

 to a slipping or faulting of the rock underlying the earth's surface has 

 been shown to be more rational. The strain caused by contraction 

 due to the cooling and other causes is relieved by such faults which 

 cause the tremors known as earthquakes. We can thus by a study of 

 topography ascertain the probable liability of a certain region to earth- 

 quake disturbances. In closing he described the wonderful instru- 

 ment known as the seismograph by means of which tremors can be 

 detected and their location ascertained at far distant points. 



The meeting then adjourned. 



Milwaukee, January 14, 1909. 



Meeting of the combined sections. 



President Teller in the chair and twelve persons present. 



