[Empiricist]

One more remark...

The suggestion that your element belongs to untypical flight instrument is not bad. Pre-WWII there was a category of "special flight instruments" manufactured mainly for test flights. The leaders of those instruments were such companies as the Smith, Sperry and Askania. From your point of view the most important is Askania because it was the German company. The Askania manufactured, among others, so-called Mehrfachschreiber. That device had a cylinder to record graphically flight parameters from four classic flight instruments. That's why I do not tell that the hybrids of altimeter/timer/barograph were impossible. But the Isgus company is totally unknown in this sector of flight instruments market. The German leader in that sector was Askania.