Cornelius Gurlitt (1820-1901) was born in the town of Altona in north-west Germany, which is now a suburb of Hamburg. He was a pianist and church organist, and amongst his compositions are two operettas, an opera entitled Scheik Hassan, piano pieces and a great deal of educational music.
This particular set of piano duets in his opus 102 and was originally published under the title Erholungsstunden (Hours of Rest). The 26 duets are an introduction to all the major and minor keys and are arranged in ascending order of sharps and flats, with each major key followed by its relative minor. The pupils part is contained within the compass of the five notes above the key-note so that, once this position is located for each piece, the correct notes will fall easily under the fingers.