Electron microscopes have also previously been used to measure magnetic properties. It is a magnificent amusement palace in neo-Baroque style, with tables in the rear section of the stalls, boxes along the sides of the circles and a balcony-terrace in the middle of the first circle. Felsenstein noted in the programme for the opening premiere of the Komische Oper: Works which had been suppressed or forgotten are once more on the programme, pieces which have seldom or never been heard — especially by composers who vanished from sight under the Nazis and are in many cases unjustly forgotten even today. In all theatres in Germany are closed, including the Metropol Theatre. What is generally known in Germany as Singspiel, Opera Buffo, Operetta or Spieloper does in part fit into the category that is meant here, but it is largely lacking in terms of both musical and intellectual aspiration. However, the relevant structures can be so small that they cannot be detected using conventional methods.