I inherited this machine from my grandmother. It is a Singer model 15. The serial number is AD778627 made in Elizabeth, New Jersey. There were 35,000 of this model made.
This is the machine I learned to sew on when I was a kid. We made quilts during the summer and in the winter she kept her potted geraniums on it. Of course the plants didn't do the finish any good and so the veneer is bad in places.
For as long as I can remember, the scarf shown in this picture has been on this machine. So we're looking at 40+ years. This is what all of the well-dressed Singers are wearing.