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THE 



POPULAR SCIENCE 

 MONTHLY 



Edited by Professor J. McKEEN CATTELL 

 of Columbia University 



With the Co-operation of Leading American Men of Science 



THE POPULAR SCIENCE MONTHLY was established by M essrs . 



D. Appleton & Company in 1872, and is in its fifty-seventh volume. 



THE POPULAR SCIENCE MONTHLY fe now published by Messrs. 



McClure, Phillips & Co., 141 East 25th Street, New York. It has a larger circulation than any 

 other purely scientific journal in the world. 



THE POPULAR SCIENCE MONTHLY is edited by Professor 



J. McKeen Cattell, Mead of the Department of Psychology and Anthropology in Columbia 

 University, Editor of Science and of the Psychological Review, and one of the best known and most 

 influential scientific men in America. 



THE POPULAR SCIENCE MONTHLY ear ly enlisted the assistance 



of the leading men of science. In the first few numbers will be found articles by T. II. Huxley, 

 John Tyndall, Herbert Spencer, R. A. Proctor, Henry Ward Beecher, Charles Kingsley, A. R. 

 Wallace, Joseph Le Conte, Henry Maudsley, Andrew U. White, John Fiske, Charles W. Eliot, 

 Francis Galton, Ernest Haeckel, and others equally distinguished. 



THE POPULAR SCIENCE MONTHLY is conducted with the ,. 



operation of the leading American men of science. A list of two hundred eminent scientific men 

 who have undertaken to give their support to the Monthly will be sent upon application. It 

 includes the most distinguished representatives of each branch of science and of each great university 

 and scientific institution. 



THE POPULAR SCIENCE MONTHLY contains contributions by 

 those most competent to write on each topic. Nothing is published that is not reliable, and nothing 

 will be omitted that is of real importance. Everything is written in a way that can be understood by 

 every one. No one can afford to neglect modern science, and every one should therefore read 

 THE POPULAR SCIENCE MONTHLY. 



McCLURE, PHILLIPS & CO 



141-155 EAST 25th STREET, NEW YORK 



