I skipped directly to chapter 3 on starting this book, since that's where Havil reconstructs the mathematics of Napier's Descriptio with modern typesetting. Havil does a wonderful job framing Napier's concerns - such as, why trigonometric functions form the backbone (no pun intended) of his method - as well as providing pseudo-code to reproduce all 45 pages of the Descriptio calculations.

I do feel the copy-editing could be tighter. It's as if Princeton merely converted the text to American spelling, while keeping British syntax. So some of the phrasing reads awkwardly, making me careful to double check the mathematics for errors that slipped into press.

Overall, a very valuable book in popular mathematics. I highly recommend for both teachers and students.