I have read and viewed the major English language texts on Sundials. These being 1.Waugh, 2. Mayall & Mayall, and 3. Rohr.

The Waugh text has good, mostly clear, intructions and gives both graphical and equation based methods of constructions. Mayall and Mayall perhaps has better graphical constuctions but Waugh excells in the variety of tables in the appendix. Waugh also has the clearest explanation of determining the declination of a wall. This is very important as many buildings are aligned along magnetic north (& south & east &west) rather than true north ( south etc...).

A shortcoming of the almost every book including Waugh, is the lack of clear instruction on how to draw other types of hours. Most importantly of these interesting alternatives types of hours are babylonian and Italian hours. These hours are still useful today. So far I've only found the Rohr text to have any attempt of explaining how to draw these lines. However the Rohr text simply doesn't match the clarity and breadth of Waugh and Mayall and Wayall.

Waugh (and Mayall and Mayall) both could do with an update on trigonometry. With the easy availability of scientific calculators, the need for log versions of equations and the use of things like "cot" functions is not needed and simply makes the calculations clumsy to perform on a key pad.

The book by Cousins is an excellent higly detailed text if you can get it, but it seems to be out of print. It is useful if you really want to get into the maths of spherical geometry and it wouldn't be the best book you'd want to read first. It makes you appreciate the wonderful elegance of the graphical solutions but it may convince you that it is all too hard when it actually isn't in a practical sense. Just about anyone can make a simple sundial.

The text by Rohr also has a good section on how to do hour lines on just about any shaped surface (bowl, sphere, plane etc..) if you have a rod for a gnomen. This is about the only strength of this text over the others.

So to conclude Waugh would be the best first text, very closely followed by Mayall and Mayall, then Rohr. The text by Cousins is excellent but at a much higher level that isn't needed for the construction for the standard types of dials.

I agree with the other reviewers...This is a very clear and concise treatment of the theory and practice of sundial construction. It is a very easy read, (anyone over the age of around 12-13 should have no difficulty with it at all,) and entertaining to boot! It has a few items that some of the other 'classics' on sundials do not. (Rene Rohr,s book "Sundials:History, Theory and Practice" and Mayall & Mayall's "Sundial's:Their Construction and Use".) The only thing this book really misses, (and the same holds true for virtually every book on sundials!) is the link between sundials telling time, and their potential use for navigation. Apart from that, this is a great book, and I highly recommend it.

This book not only covers everything from time itself to noon marks to fancy sundials, it is well written and fun to read - a rare combination in a "technical" book.