Mobilite was made by The S. H. Thomson Mfg Co. of Dayton, Ohio. Do you have a picture of it?
They were manufactured starting in 1921, and featured a disc or ball style handle.
Sorry no pics of the light mounted, but here are a couple
of patents that have some drawings of the closest model.
Inventor - Robert H. Hummert The S. H. Thomson Mfg Co Dayton. Ohio Spot-Light Patent number: 1811502 Filing date: Sep 7, 1929 Issue date: Jun 23, 1931 http://tinyurl.com/36nfvyt
Inventor - Robert H. Hummert The S. H. Thomson Mfg Co Dayton. Ohio Electric Switch Mount Patent number: 1918845 Filing date: Nov 13, 1929 Issue date: Jul 18, 1933 http://tinyurl.com/3ancgko
Regards
Art
Ps. It’s likely they supplied the light packaged with
the correct bracket for the make or model it was to be
used on, so the drawings would be somewhat generic.
AJ