Originally Posted by Rollo
Two books on the subject:
The Adventure of English - Melvyn Bragg:
This book looks at how the English language, survived invasions of Romans, Franks, Saxons, Jutes etc, and how it was able to absorb and evolve. It's written in a rather easy sort of conversational tone and shouldn't take more than a fortnight to read.
Mother Tongue - Bill Bryson:
Bryson's book is more concerned with how words arrived in English and travelled around the world. It touches on many topics that the other book does, but because it is now one of the "Popular Penguin" series, you can pick one up for less than a fiver.