A history of the circle
However, it is difficult to see what readership this book is intended for. The various examples given in the book are reasonably interesting if you don't already know about them, but I felt that none of the discussion was deep enough to satisfy a reasonable knowledgable reader. On the other hand there are quite a few equations in the book - even differential equations. Now you don't have to understand this mathematics in order to follow the book but I feel that it is likely to put off a beginner in the subject. The one group who might find the book of use are those who are at the start of the study of calculus, and want to see how it relates to the real world.