This is just a little piece to demonstrate the "light full organ" of the big Müller.
You'll notice that the sound of the "tierce" is prominent in this dialogue between the Hoofdwerk and the Rugwerk, which are coupled.
I know nothing about Christian Friedrich Schale (1713-1800), but I THINK he may have been a student of J.S. Bach - although you'd NEVER know to listen to this... ;-)
Any other info about him would be GREATLY appreciated!