The Day Clock
One of the first clock watches was invented by a clockmaker from Nuremberg named Peter Henlein in the 15th century. In order to keep it running, the person needed to wind the clock every now and then to keep the tension on the mainspring. Then in the 17th century, a Dutch polymath named Christiaan Huygens designed the pendulum clock. Both of these inventions were used to tell the time, but no one ever thought about creating a day clock to figure out which day it was like this super useless device.