Singers were made in Podolsk, Russia from 1905 until the revolution in 1917. Before the factory in Podolsk was opened, the machines were made in Germany and imported into Russia. The serial numbers began with A, E, and T, and 100 with S. I am not sure the detailed records survived the revolution. Have heard that Singer reopened the plant in 1994. So the date of 1915 would be consistent with manufacture in Russia.