Complex sentence: His most famous horological book "The Marine Chronometer, its History and Development" was first published 1923 by J.D. Potter and was the first scholarly monograph on the subject, and was generally considered the authoritative text on marine timekeepers for at least half a century.
Split into simpler sentences: His most famous horological book, "The Marine Chronometer, Its History and Development," was first published in 1923 by J.D. Potter and was the first scholarly monograph on the subject. It was generally considered the authoritative text on marine timekeepers for at least half a century.