Had no idea my self. Glad to know that there actually was a reason to have it with a sewing machine. thank you, deplaylady, for your pictures and explanation.
M.I.Late, I agree with you. These do look like contraptions that would cause awful bodily harm!!
It amazes me that the regular housewife was trusted with such devices when women were thought to be dim minded. Now we could never be trusted to oil andlubricate the machine!!