Who knows the relation between Curtas and the Petersson calculator from (around) 1870?

Does anybody know the technical history of the Curta? How much is the Curta technology related by the so called “Petersson calculator?” I did not find a reference in Curt Herzstark’s biography that he was inspired by the Petersson calculator. You can find a Petersson calculator in the Tekniska Museet (that is the “Technical Museum”) in Stockholm.

Here is a picture: http://www.rechnerlexikon.de/artikel/Bild:Petersson-Calculator-Tekniska-Museet-Stockholm.jpg

Here are more pictures of the inside: http://www.rechenmaschinen-illustrated.com/Petersson.htm

This is a 70 page long article about the machines made by Christel Hamann, Paul Haack, Axel Jacob Petersson, unfortunately only in German language: http://www.boelters.de/Rechenmaschinen/_Hamann/Hamann_Haack_Pat.pdf
The article give more references for further reading.

One can see in the photos of the latter two links that the Petersson calculator is a central stepped drum machine just like the Curta, so it does not only look like a Curta but it works with the same technical principle, more than 70 years before the first Curta appeared.

Sorry for asking yet another question, I hope I am not abusing this forum by writing too many posts.....

Wow, this is a very interesting machine. Never heard anything about this calculator. Seems that nobody knows more about it and its relation to the Curta. Perhaps there is no relation at all.