Popular Science Library

EDITOR-IN-CHIEF

GARRETT P. SERVISS

AUTHORS

WILLIAM J. MILLER    HIPPOLYTE GRUENER    A. RUSSELL BOND
D. W. HERING    LOOMIS HAVEMEYER    ERNEST G. MARTIN
ARTHUR SELWYN-BROWN    ROBERT CHENAULT GIVLER
ERNEST INGERSOLL    WILFRED MASON BARTON
WILLIAM B. SCOTT    ERNEST J. STREUBEL
NORMAN TAYLOR    DAVID TODD
CHARLES FITZHUGH TALMAN
ROBIN BEACH

ARRANGED IN SIXTEEN VOLUMES
WITH A HISTORY OF SCIENCE, GLOSSARIES
AND A GENERAL INDEX

ILLUSTRATED

VOLUME TWELVE

P. F. COLLIER & SON COMPANY
NEW YORK