This is a second one. The ad said it was from 1879. The seller got the serial number wrong and it's from 1888. Still, it has a bobbin winder and looks better than the other one.
I'll have to sell it in the cabinet, since I have no space (sad, right?).
After a few hours of cleaning it's working perfectly and I wish I could keep it to sew a garment with.
The 15 is an amazing machine and this is the only fiddle base machine Singer made with a round bobbin
and standard needle.