Volume 7

1971

Issue 1

It has been said that "behind every great computer there is a great memory". As with most sayings, of course, this is not the whole story.

Issue 2

Early in the 17th century, Johannes Kepler established, from actual observations of the positions of the planets in the sky, three laws of planetary motion.

Issue 3

This is an account of some elementary aspects of the subject known as "algebraic topology". It investigates the placing of nets on surfaces and Euler characteristics.