If you are interested in the English language and how it has evolved over the years then A Higher English Grammar by Alexander Bain is a great choice to read. Bain was a Scottish philosopher and educationalist in the 19th century and was played a significant role in psychology, educational reform and linguistics.
He was appointed Regius Chair of Logic and the Regius Chair of English Literature at the University of Aberdeen in 1860 and it was during his time in these roles that he wrote A Higher English Grammar. It is an interesting and in-depth look at the English language both written and spoken and also includes a fascinating and complex look at etymology, as well as thoroughly investigating the correct use of verbs, adverbs, adjectives and nouns.
A well written book aimed at both the student and the general reader, Bain's meticulous and exhaustive look into the world of language is both astounding and stimulating; a truly great read for anyone interested in this subject.