Below the Observatory at Greenwich, in front of the National Maritime Museum, is a beautiful statue of the two dolphins featured in their coat of arms. If you look where their shadows fall onto the bronze plate below, you can tell the time correct to one minute, whatever day of the year it is. The designer of that sundial wrote this book. It has a hundred and twenty colour pictures ranging from early dials scratched on church walls through 16th and 17th century multidials to modern dials of an incredible variety of design. The text tells you what the different dials are, how they work and something of their history. It is a lovely book by an internationally famous authority.