Chemistry.
By Ira Remsen, President of the Johns Hopkins University.
Astronomy.
By Simon Newcomb and Edward S. Holden.
Geology.
By Thomas C. Chamberlin and Rollin D. Salisbury, Professors in the University of Chicago.
Physiography.
By Rollin D. Salisbury, Professor in the University of Chicago.
General Biology.
By William T. Sedgwick, Professor in the Mass. Institute, and Edmund B. Wilson, Professor in Columbia University.