THE

POPULAR SCIENCE

MONTHLY.

CONDUCTED BY E. L. AND W. J. YOUMANS.

D.

VOL. XVIII.

NOVEMBER, 1880, TO APRIL, 1881.

NEW YORK:

APPLETON AND COMPANY,

1, 3, AND 5 BOND STREET.

1881.

COPYRIGHT BY

D. APPLETON AND COMPANY.

1881.