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.