The D9 was the home machine W&W made before Singer took over.
Singer continued with the "D9" in late 1905 until c. 1908. Only noticeable difference between the two is Singer put their part numbers on some of the parts. Referred to as 9W1 in Singer catalogs for treadle model.
In c. 1908, Singer modified the D9 to fit Singer cabinets and had Singer decals. Referred to as 9W7 for treadle model.
In c. 1913, the 115 replaced the 9W7. The 115 is mechanically similar to the D9 and 9W7 but the appearance is like a Class 15.
I believe the 115 was replaced with the 101 in the 1920's, not quite certain.
Jon
Last edited by jlhmnj; 11-15-2016 at 08:34 AM.