Cathy,
Thanks for the great informative post. I need to get my act together on the history . So much info makes my old brain spin. You have an intriguing method to your collection. Not that broad a selection here in East Tennessee. Oh, and thanks for clarifying which Boye case you are using.
If I may make a note, the Singer 15 is not rotary, rather it is oscillating. Maybe you meant to type Singer 115?
Maria
Smoky Mountains of Tennessee