Andrew Dougherty first secured a patent for “Triplicates” in 1876, a novel type of indices with a miniature card in the top left-hand corner (and bottom right). These kept Dougherty at the forefront of innovation. There are several variations in the size and design of the “Triplicate” indices, with the smallest being the earliest. Dougherty's “Triplicate” playing cards have a specially designed Ace of Spades which was intricately engraved, with a spread of cards inside the central Spade symbol demonstrating the innovation.
Above: Triplicate No.18' playing cards by Andrew Dougherty, c.1878. This is the second version of the brand with a 'Little Joker' card instead of a 'Best Bower' and a more elaborate Ace of Spades with the addition of two cherubs and an eagle at the top. Image courtesy Rod Starling.
Dawson, Tom & Judy: The Hochman Encyclopedia of American Playing Cards, U.S. Games Systems Inc., 2000
Hargrave, Catherine Perry: A History of Playing Cards and a Bibliography of Cards and Gaming, Dover Publications, New York, 1966
Images from the collection of Rod Starling, author of "The Art and Pleasures of Playing Cards".