Fascinating, thanks very much for posting! I had never heard of a Curta before.
I'm still trying to make it work, but it's fun to play with and looks like it was a very important innovation for it's time.
I'm dating myself, but I had a Curta Calculator back in the 60's. I was involved in road rallies and calculating speeds to make the next checkpoint was the job it was used for. If you had to slow down, you could figure out what speed you needed to go to make the average.
I wish I still had it. They bring big bucks on eBay right now.