Got curious when I saw patent date on the sight, there were only two firearms related patents assigned on May 17, 1887 (if I remember right it was a Tuesday).
The patent is just for the eye piece on this sight, there is a different type elevation shown in the patent drawings. It was never assigned to Steven's and the inventor was George Washington Hadley -
patent/US362956 The text is poor through GOOGLE so many words are incorrectly spelled, they apparently used a text recognition program on old scans of the original - even the inventors last name is wrong, a scan of the original is on the USPO web site but their site is harder to use. Here it is on the USPO web site -
uspto.gov/.piw?Docid=00362956 - GOOGLE give a link to this on the right side of their screen.
I could not find anything on the rest of the sight, there is a patent from 1920 for either an improvement of, or a very similar sight, that was assigned to Steven's -
patent/US1338183 This seems very late for that type of sight, a USPO screen will load and you then have to click images.
Rick, are there any other dates stamped on the sight?
Trivia - May 17, 1887, it was a Tuesday and there were 2 firearms related patents issued that day -
May 17, 1887 ...out of a total of 439 patents -
May 17, 1887 total ...out of 21,442 issued that year (includes 99 reissues) -
Patents issued for all of 1887 ...of that total, 125 were firearms related -
Firearms patents issued in 1887 
