The 1917 patent is #1,245,860, which covers the pistol grip and trigger-like switch. And yes, the inventors were Samuel Duncan Black and Alonzo Galloway Decker - the founders of Black & Decker Manufacturing. The next patent that they got for electric drills was USD 57,579 [The "D" indicates a Design patent], which issued April 26, 1921. Most of the early B&D nameplates list only the dates, which would indicate that yours was made between 1917 and 1921. Great score! I don't have any with only a single patent date listed, so mine are all newer. Somewhere in the mid to late 1920s, they had some nameplates with actual patent numbers instead of the dates. Member JohnsIronSanctuary has an early 1/2" B&D; see
http://s1202.photobucket.com/albums/bb373/johnsironsanctuary/OLD%20POWER%20TOOLS/.
One of mine is in the 1924 - 1926 range; by that time, they mention Towson, Maryland: "Patents. Nov. 6, 1917; April 26, 1921; April 29, 1924. For Service send this complete tool to nearest factory branch. Chicago, San Francisco, New York, Buffalo, Seattle, Cleveland, Detroit, Los Angeles, St. Louis, Boston, Minneapolis, Kansas City, Dallas, Philadelphia, Atlanta. Factory Towson Maryland."
The extra handle on top of the pipe auxiliary handle is likely from another drill. Quite a few brands had rear handles that could be placed in horizontal or vertical positions, and some could be rotated continuously - but I've never seen one on the end of the auxiliary pipe handle, on ANY brand. I haven't seen either the loop handle, or the shoulder-pad type on the rear of yours, exactly like yours. Most of the B&D rears had a hand-grip loop portion, with flat pads extending both sides for use as a breast drill. Usually, these had the B&D logo cast into them, often with a sort of knurled background grip area.
