Eduard Becker from from Solingen, Germany was issued German Patent #70879 on March 7, 1893 for the Columbus Corkscrew. He subsequently received English Patent #17,924 October 28, 1893. On April 10, 1894 Becker was granted American Patent #518,018 for this corkscrew.
The ring hold the split barrel together during cork removal. Once the cork is removed from the bottle, the ring is moved up, the sides split and the cork can be removed from the worm.
Many variations of handle and frame design exists. In the above photo, the "Columbus" in the middle is marked GAUMEN, INDUSTRIAS ARGENTINA, M.REG. It is one of only three corkscrews from Argentina in my collection................Don Bull