This book, a reprint of a successful English publication, has been so enlarged as to be to all intents and purposes new. It has been carefully revised by a Reverend gentleman, who for some time filled the chair of Physics and Chemistry in one of our colleges. Recent inventions and improvements are described in a simple, popular style, so as to be easily understood by all, and short notices are given of prominent inventors and scientists. The paragraphs relating to doctrinal matters conform in every respect to the teachings of the Church. A feature which will commend the book to every teacher is the definitions of difficult words and terms, following the paragraphs in which such words occur.