Here is an image showing a cut-away drawing of a drill similar to yours, taken from a 1923 B&D catalog on the Internet Archive site.
38 p., illus., 27.6 cm, trade catalog
archive.org
This might be your model. It also has a 1/2" capacity chuck. It looks like the D handle has been removed from your drill.
They were Very Expensive, back in the day. An inflation calculator says that would be $1,867 in today's dollars.