X TABLE OP CONTENTS. 



PAGE 



January 20, 1890. 



PROF. G. FREDERICK WRIGHT, LL.D. 



The Ice Age in North America and the Antiquity of Man 83 



February 17, 1890. 



DR. H. CARRINGTON BOLTON. 



Four Weeks in the Desert of Sinai .... 104 



March 3, 1890. 



PROF. R. W. RAYMOND, PH.D. 



The Grand Canon of the Colorado 128 



March 17. 1890. 



PROF. CHARLES A. YOUNG, PH.D. 



Nebulae and the Nebular Hypothesis 13& 



March 31, 1890. 



PROF. CHARLES F. CHANDLER, PH.D. 



Volts and Amperes, and what they mean 137 



April 14, 1890. 



MAJOR GEORGE M. STERNBERG, M.D., U. S. A. 



Methods of Research in Bacteriology 139 



April 28, 1890. 



WILLIAM BRADFORD, ESQ. 



Glimpses of Arctic Scenery 156 



May 19, 1890. 



GEORGE F. KUNZ, ESQ. 



The Paris Exhibition of 1889 20 



