@njuffa sry, I was wrong in my last comment. The separate objects are cone-shaped. And indeed, the manufacturer's name remains partly as "W.J. Rohrb*" from Berlin. Does this help you classify the object?

Thanks for your comments. I'll provide more photos asap. The separate object is semispherical. The object must be from 1829–1909 or newer (but less likely). Today's owners would not like to disclose the original owner's (OO) name for privacy reasons. But the OO was a later-founded Swiss Society of Natural Sciences member. Also, this link e-periodica.ch/digbib/view?pid=sng-005%3A1864%3A48#230 describes devices they used, but none of the descriptions matches, afaik.