eight day rolling ball timepiece, made by Bell Winchester, from the design patented by Sir William Congreve, F.R.S. in 1808 The steel ball takes 15 seconds to roll from one end of the table to the other. At each end a catch is released, enabling the spring-driven movement to tip the table the other way. Green velvet and mahogany and brass base including a glass cabinet. The mainspring has to be wound eight days. The ball travels about 3900km each year.
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