with his wife, Florence Tebb Weldon, who was his computer. Weldon used logarithms and mathematical tables created by August Leopold Crelle and had no calculating machine. Karl Pearson, who had a lab at the University of London, felt that the work Weldon did was "hampered by the committee". However, Pearson did create a mathematical formula that the committee was able to use for data correlation. Pearson brought his correlation formula to his own Biometrics Laboratory. Pearson had volunteer and salaried computers who were both men and women. Alice Lee was one of his salaried computers who worked with histograms and the chi-squared statistics. Pearson also worked with Beatrice and Frances Cave-Brown-Cave. Pearson's lab, by 1906, had mastered the art of mathematical table making. Mathematical tables Human computers were used to compile 18th and 19th century Western European mathematical tables, for example those for trigonometry and logarithms. Although these tables were most often known by the names of the principal mathematician involved in the project, such tables were often in fact the work of an army of unknown and unsung computers. Ever more accurate tables to a high degree of precision were needed for navigation and engineering. Approaches differed, but one was to break up the project into a form of piece work completed at home. The computers, often educated middle class women who society deemed it unseemly to engage in the professions or go out to work, would receive and send back packets of calculations by post. The Royal Astronomical Society eventually gave space to a new committee, the Mathematical Tables Committee, which was the only professional organization for human computers in 1925. Fluid dynamics Human computers were used to predict the effects of building the Afsluitdijk between 1927 and 1932 in the Zuiderzee in the Netherlands. The computer simulation was set up by Hendrik Lorentz. A visionary application to meteorology can be found in the scientific work of Lewis Fry Richardson who, in 1922, estimated that 64,000 humans could forecast the weather for the whole globe by solving the attending differential primitive equations numerically. Around 1910 he had already used human computers to calculate the stresses inside a masonry dam. Wartime computing and electronics It was not until World War I that computing became a profession. "The First World War required large numbers of human computers. Computers on both sides of the war produced map grids, surveying aids, navigation