Mechanical Puzzle Collection

The company Richter from Rudolstadt began producing large amounts of Tangram-like puzzles of different shapes, the so-called “Anker-puzzles”.
In 1893 professor Hoffman wrote a book called Puzzles; Old and New. It contained, amongst other things, more than 40 descriptions of puzzles with secret opening mechanisms. This book grew into a reference work for puzzle games and modern copies exist for those interested.