A 3D model of U.S. Pat. No. 984,969 -- cutting edge 1910 screw technology!
"To all whom it may concern:
Be it known that I, HENRY G. REINIGER, a citizen of the United States, residing at Rathdrum, in the county of Kootenai and State of Idaho, have invented a certain new and useful Improvements in Screws, of which the following is a specification."