week 45 The basses of the three tuba stops. The trebles of the tubas stops. From 2'-pitch pipes are of double length (harmonique). At the left the swell shutters. Rear view on the Tuba Magna 16'. Note the harmonic trebles pipes and the extra high boots of the basses to ensure free speech of the mitered resonators. View from below. At the top of the picture the swell shutters. This is the entrance to tune the Cor Harmonique 4' (the stop at the front side of the windchest).