I saw this article about Helen Keller's unique pocketwatch on Neatorama and wanted to share.
Helen received this "touch watch" when she was twelve, from John Hintz, the superintendent of the Volta Bureau. The Volta Bureau was constructed in the 19th century by Alexander Graham Bell as a place to house information about the deaf and hard of hearing. (You may know it as the Alexander Graham Bell Association for the Deaf and Hard of Hearing.)
According to the National Museum of American History, "This uncommon watch has a case studded around the edge with pins that correspond to the hours on the watch dial. A revolving hand stops at a point between the pins that corresponds to the hour and approximate minute. With the hand and pins as locators, it was possible to feel the approximate time in the dark or, in the case of a diplomat like Hitz, discreetly."
Very interesting! I'd love to play around with something like this.