I didn’t know that when I started this thread. However, I realized that when I searched the link provided by Chinghis. I agree with the comment in that post that this must have been a precursor to more functional designs.

I think that even two very able bodied, similar sized people with a great sense of balance would have real difficulty using this model - hence the comments. But it is an admirable goal and I’m glad they’ve come up with more practical designs.