Nearly all puzzle books published today grossly underestimate the intelligence of their public. The reader can no longer be enter-tained with the simple match-trick or coin puzzles, neither does he want to see problems purely mathematical in nature, such as can be found in any textbook. We have tried to produce a book of those puzzles which lie between the two extremes.

Although most of the problems can be solved by logic and common sense, some of them may also be solved more elegantly by mathematics.

The essential ingredients of a good puzzle are not hard to establish. It should be ingenious but clear, complete yet concise, if possible amusing, and have a unique solution. It is for oUr readers to decide how many of these puzzles bear comparison with this ideal.

Completely new ideas for puzzles are unfortunately rare and so we do not apologise for including a few of the "Aged but not infirm". Many of the problems are original and we claim to have improved others.