This type of current meter was designed by an American, Joseph Saxton (1799-1873) in 1832, while he was working in London. The meter is attached to a pole and immersed in a stream of water, the string is pulled up and this allows the propeller worm screw to engage with the cogged water wheel. One revolution of the propeller blade equals one foot of water passing by. On releasing the string, the wheel is locked enabling a precisely timed reading to be taken. The brass current meter consists of large direction plate, rod holder, worm screw, circular gauge with locking device, pull string and single blade propeller. A small manuscript drawing of the current meter is also in box.