What is a/the sidereal pendulum?

i was reading a book about the nazis and it was discussing the makeup of the early party. it said that one of them, can’t remember who, was a real crank mystic, and as evidence, pointed out that he believed in the ‘sidereal pendulum’. So, what is this?

All I can find…

http://www.dagobertsrevenge.com/index.html?articles/levenda

Here is a very long page where they have a sidereal pendulum for sale:

Here is just the picture of it.

thanks to both of you gentle people!