THIS little book purports to serve as an introduction to the great problems of space, time and motion. The inquiries it is concerned with are very old. Men have been forming ideas concerning space and time since times immemorial, and curiously enough, have been writing and fighting about these things with the greatest interest, even fanaticism.

This has been a strange strife, indeed, having little to do with economic necessities; it has always dealt with abstract things, far removed from our ...