THE

POPULAR SCIENCE

MONTHLY.

CONDUCTED BY E. L. YOUMANS.

VOL. VII.

MAY, 1875, TO OCTOBER, 1875

'NEW YORK:

D. APPLETON AND COMPANY,

549 & 551 BROADWAY.

1875.

ENTERED, according to Act of Congress, in the year 1875,

BY D. APPLETON & CO.,

In the Office of the Librarian of Congress, at Washington.