I have come across several old European parlor guitars with a globe stamp on the bottom. Often you can make out the words "Trade mark" in the stamp. Alternatively the same type of globe stamped on the back of the headstock. I have always wondered who used that logo. Now I found the following text online about a similar guitar with a globe stamp on the headstock:

"On a German guitarsite they told me now that this is a "Biedermeier" style guitar which was popular in the first half of the 19th century and later had a renaissance at the beginning of the 20th. So this one is from the beginning of last century. It was supposedly made in the Markneukirchen Area, which has been a musical instrument Mecca for 350 years. The globe is supposed to have something to do with "Weldklang" (worldsound) a company which used the globe as their logo and which sold many different instruments by subcontractors, apparently also guitars, but that this history has been very sparingly documented.”

The mystery seems to be solved!

Edit: New information has come to light. Per Linder found a former German company with a globe as its logo;  G.A. Pfretzschner. There was even a receipt from JP Sjöberg in Sundsvall! I also received a picture of the logo that I have seen several times inside old European parlor guitars, but which I could not find again, a picture of which was submitted by Anders Lindberg.