In 1843 Tsar Nicholas I of Russia informed the Duke that he was likely to visit Chatsworth the following year. In anticipation of this visit, William Cavendish, 6th Duke of Devonshire, decided to construct the world's highest fountain, and set Joseph Paxton to work to build it. An eight-acre (32,000 m2) lake, the Emperor Lake, was dug on the moors 350 feet (110 m) above the house to supply the natural water pressure.