BY

IRVING FISHER, _Chairman_,
PROFESSOR OF POLITICAL ECONOMY, YALE UNIVERSITY

AND

EUGENE LYMAN FISK, M.D.,
DIRECTOR OF HYGIENE OF THE INSTITUTE

_NINTH EDITION_

FUNK & WAGNALLS COMPANY
NEW YORK AND LONDON
1916

COPYRIGHT, 1915, BY
FUNK & WAGNALLS COMPANY
(Printed in the United States of America.)

* * * * *

_Published, October, 1915_
_Second Edition, November, 1915_
_Third Edition, December, 1915_
_Fourth Edition, March, 1916_
_Fifth Edition, April, 1916_
_Sixth Edition, May, 1916_
_Seventh Edition, June, 1916_
_Eighth Revised Edition, September, 1916_
_Ninth Edition, September, 1916_

FOREWORD

To one who has been an eye-witness of the wonderful achievements of
American medical science in the conquest of acute communicable and
pestilential diseases in those regions of the earth where they were
supposed to be impregnably entrenched, there is the strongest possible
appeal in the present rapidly growing movement for the improvement of
physical efficiency and the conquest of chronic diseases of the vital
organs.

Through the patient, intelligent and often heroic work of our army
medical men, and the staff of the United States Public Health Service,
death-rates supposedly fixed have been cut in half.

While it is true that to the public mind there is a more lurid and
spectacular menace in such diseases as small-pox, yellow fever and
plague, medical men and public health workers are beginning to realize
that, with the warfare against such maladies well organized, it is now
time to give attention to the heavy loss from lowered physical
efficiency and chronic, preventable disease, a loss exceeding in
magnitude that sustained from the more widely feared communicable
diseases.

The insidious encroachment of the chronic diseases that sap the vitality
of the individual and impair the efficiency of the race is a matter of
increasing importance. The mere extension of human life is not only in
itself an end