BY

CLEMENT REID, F.R.S.

Cambridge:
at the University Press
1913

Cambridge:
PRINTED BY JOHN CLAY, M.A.
AT THE UNIVERSITY PRESS

With the exception of the coat of arms at

the foot, the design on the title page is a

reproduction of one used by the earliest known

Cambridge printer, John Siberch, 1521

PREFACE

Knowledge cannot be divided into compartments, each given a definite name and allotted to a different student. There are, and always must be, branches of knowledge in which several sciences meet or have an interest, and these are somewhat liable to be neglected. If the following pages arouse an interest in one of the by-ways of science their purpose has been fulfilled.