ASTRONOMERS. By E. J. C. Morton, B.A. With numerous diagrams.

BOTANISTS, ZOOLOGISTS, AND GEOLOGISTS. By Professor P. Martin Duncan, F.R.S., &c.

CHEMISTS. By M. M. Pattison Muir, Esq., F.R.S.E. With several diagrams.

MECHANICIANS. By T. C. Lewis, M.A.

PHYSICISTS. By W. Garnett, Esq., M.A.