My first machine is a National Sewing Machine Company Vibrating Shuttle treadle. The "Damascus" name was manufactured for Montgomery Ward. The serial number is 3209025. I don't know exactly in which year it was made. There is no list for NSMCo machines like there is for Singer. I'm guessing in the 1920s.
My second machine is a Singer 128K Hand Crank, manufactured in Scotland on Feb 2, 1927, serial number Y4467698.
My third machine is a Singer 221 Featherweight, manufactured in Elizabeth, NJ on January 24, 1940, serial number AF741157.
Beautiful machines. I have never heard of a vibrating shuttle. Love the cabinet for the treadle. :)