I can hardly give enough compliments to this (and its predecessor the Princeton Companion to Mathematics).  The scope is broad, the articles are all incredibly well-written and cover a wide range of interesting topics.  This volume focuses on applied mathematics, which means it is of more direct use to scientists than the previous volume (though I still highly recommend the previous volume) and not  just in physics.  There are plenty of biology, chemistry, and engineering examples throughout the book.  The book is well-structured though it still has a bit of an encyclopedia-like broadness.  If you have a specific application in mind and it's covered, this is a wonderful way to be introduced or to remind you of the ways of approaching the application.<br><br>The book is quite readable.  Few will plow all the way through, but I was delighted to take a chapter almost every day.  Even if the topic wasn't something I'd usually look at, I knew that it would be presented well and maybe give me some new way of looking at the world.