The Popular Science Monthly, June, 1900 / Vol. 57, May, 1900 to October, 1900

Transcriber’s note: Table of Contents added by Transcriber.
EDITED BY J. McKEEN CATTELL
VOL. LVII MAY TO OCTOBER, 1900
NEW YORK AND LONDON McCLURE, PHILLIPS AND COMPANY 1900
Copyright, 1900, By McCLURE, PHILLIPS AND COMPANY.
PROFESSOR WOLCOTT GIBBS,
President of the National Academy of Sciences, Emeritus Rumford Professor and Lecturer on the Applications of Science to the Useful Arts at Harvard University.

JUNE, 1900.
It was due to certain particularly favorable circumstances that the first ideas on preventive inoculation were gathered from observations on smallpox patients. Such circumstances were presumably the following:
a. It is a disease which attacks epidemically, in a short time and within a small area, large numbers of people, thus permitting of easy comparisons and suggesting conclusions from the facts observed.
b. Its fatality is comparatively small, so that after each outbreak a large number of convalescent persons remain alive to serve as objects for future observation and comparison.