Mathematical Tables Project
An American unemployment relief scheme that put 450 people to work computing by hand, and became the largest human calculating engine of the twentieth century.
It began in 1938 in New York under the Works Progress Administration, with Arnold Lowan in charge administratively and Gertrude Blanch in charge mathematically. The staff were Depression unemployed, most with no mathematics beyond the four operations. Blanch sorted them by what they could actually do: a group that could add, a group that could subtract, and separate procedures for negative numbers because not everyone could handle them. The computing schemes were designed so that each step was a single operation, and so that an error broke the pattern of the table and therefore showed.
The output ran to 28 volumes of tables, plus commissioned work for ballisticians and for the Manhattan Project. In 1948 the operation moved to the National Bureau of Standards, and its successor published the Handbook of Mathematical Functions in 1964 — Abramowitz and Stegun, for decades the most cited work in all of science. The obvious observation: the division of labour de Prony devised in 1791 was scaled here to 450 people, and a decade later replaced by one machine in one room.