Awesome! A buttonholer on a Singer treadle sewing machine, making perfect buttonholes.
This is amazing technology IMO, from the 40’s.
On a treadle sewing machine the needle is fixed. It can’t move side to side like modern electrics so it can’t do a zigzag stitch.
How to get around that? Let’s grab the fabric and move it side to side while the needle goes up and down- voila, zigzags and buttonholes!
Unlike how a computer works, I can look at this and understand how it works, and I think it’s exceedingly ingenious, harnessing the mechanical drive of the sewing machine and controlling the whole circuit of the buttonhole, instead of the three stage variable length method I learned on electric machines.
Treadle sewing machines can still outperform electric machines, mostly by being stolid and consistent, while electrics can be buggy and finicky.