An architect by profession, George Ashdown Audsley (1838-1925) had occupied himself, as early as 1865, with the problems of organ building. But 39 years later, in 1904, he designed what was then the largest organ in the world--140 stops on five manuals--for the St. Louis Exposition. Striving to make the organ as "expressive" as possible, he proposed that registers of a division be divided into subdivisions. The result was that a variety of stop combinations had increased immeasurably. This 1921 classic by the renowned author provides organists and all those interested in the instrument with a guide to the organ's numerous stops and gives their various names in different languages, traces their origins, describes their construction, tonal characteristics, and their value in artistic combination and registration. Of interest to students, teachers, and professionals, this book about the "Monarch of all Instruments" is a must for any organist's library. Unabridged republication of the edition published by The H. W. Gray Co., New York, 1921. 5 plates of illustrations. Glossary.