Design patent #D12,855 April 11, 1882 by George S. Barkentin, assigned to P & F Corbin. Shown on page 554 of the 1885 Corbin catalog. Two slightly different versions offered. Numbers 2837 & 2838 are more spherical.D-10610is the other version.  In this version the band around the is smooth and the stem takes a threaded spindle.