The Harmonium School (Op. 5) was written by Ernst Stapf and first published in German as Praktische Anleitung zum Harmonium-Spiel. It is a practical guide to playing the Harmonium (or American Reed Organ) and a rare example of the wide range of method books that were published during the heyday of the instrument in the latter part of the 1800s and the early 1900s.Stapf wrote few works that have survived to this day but is perhaps best known as the arranger and editor of a popular series entitled the Harmonium Album in which he gave simple one- and two-manual arrangements of classic works by the greatcomposers including Beethoven Bach and Handel.