The hydraulic crane was invented by Sir William Armstrong in 1846, primarily for use at the Tyneside docks for loading cargo. These quickly supplanted the earlier steam driven elevators: exploiting Pascal's law, they provided a much greater force. A water pump supplied a variable level of water pressure to a plunger encased inside a vertical cylinder, allowing the level of the platform (carrying a heavy load) to be raised and lowered. Counterweights and balances were also used to increase the lifting power of the apparatus.