Since the cape pieces get big, I started a small project that would be more portable. It's a pair of slippers from the same book as the bicycling sweater, Butterick's
Fancy and Practical Knitting. The same pattern is in both the 1897 and 1901 editions.
I finished the first upper today.

It blithely tells you to sew the uppers to soles so I presumed you used to be able to purchase soles. I've seen quite a few patterns from the Victorian era through the 1940's that are just for the uppers for slippers. Evidently you can still buy soles, though I had presumed that was a thing of the past. That being said, a lot of the hits were for Etsy shops overseas so they're clearly not available in the same way they used to be. (Knit Picks carries some two-piece soles but not single piece soles, which seems weird.)