Whist Patents.

...Patent No 552,732, granted January 7, 1896, to Luther C. Slavens, Jr., Westport, Mo. Apparatus for playing duplicate whist, consisting of a series of trays, each of which is provided with holders for the several hands, and a character upon each tray to distinguish it from the others, and an auxiliary tray provided with a number of holders equal to the number of playing trays, each holder on said auxiliary tray being provided with a character corresponding to the distinguishing character of one of the playing trays.

The Whist Reference Book.
William Mill Butler, John C. Yorston Publishing Co., Philadelphia 1899.