This odd-looking rifle invented in 1854 by British engineer T.W. Treeby was an early attempt to vastly increase the ammunition capacity of rifles. At the time, rifles had to be loaded from the muzzle one bullet at a time.
The Treeby gun instead cycles fourteen individual chambers on a chain, each of which is preloaded and given its own percussion cap. Between each cycle, the user turns a handle to unseal and then reseal the barrel.
Link -via The Firearms Blog