France's first full team of computers, however—people making calculations in an organized network that would foreshadow computers of a more mechanical variety—was assembled in the early 1790s by Gaspard de Prony, the engineer and mathematician who would be known, later on, for his work with hydraulics. These human computers had a typically France-post-revolution assignment: to produce logarithmic and trigonometric tables that would help France in its work of decimalizing trigonometry. (The goal? To do for angle measurements what the metric system was doing for mass and length, democratizing measurement for a new republic.)

Women at work tabulating during World War II (Shorpy)

The group was typically post-Revolutionary in another way, as well: It was composed of wig-makers who had been rendered unemployed with the economic downfall of the aristocracy. In that, the group's work set a significant precedent: It "conferred no prestige." It was factory labor, essentially, that required mental concentration instead of physical. It was, as the Christian Science Monitor had it, "numerical needlework."

In other words, it was ideal work, at the time, for women. There were economic reasons for this (women, Grier notes, would generally "work for half of what similarly skilled men would"), but there were also more gender-specific rationales. In the mid-twentieth century, Father Roberto Busa, an Italian Jesuit priest, partnered with IBM to index the vast writings of Thomas Aquinas via a collection of coded punchcards. The Index Thomisticus was perhaps the earliest large-scale effort in the field of the digital humanities, and it relied, Melissa Terras notes, on female computers to render its calculations. (Father Busa chose women for this task, one of his colleagues recalls, "because they were more careful than men.")

A woman transcribes Aquinas's writings to punch cards. (CIRCSE Research Center, Università Cattolica del Sacro Cuore, Milan, Italy via Creative Commons)

There were other groups like this. Pickering's Harem (more politely: the "Harvard Computers") processed astronomical data in the late 19th century. Annie Jump Canon, one of Pickering's hires, used astronomical calculations to develop the Harvard Classification Scheme. Another computer, Henrietta Swan Leavitt, made discoveries that would lead Edwin Hubble to develop his theories about the expansion of the universe. And the wives of scientists working at Los Alamos were often recruited to compute long math problems that would inform the technologies of the Manhattan Project.

War brought more females to the field, as it did in other technological industries. As men fought world wars, and as the wars themselves increased the demand for computing power, even more women took on roles as human computers. By the time World War II broke out, many scientists and industrialists in the U.S. were measuring computing power not in megahertz or teraflops, but in "kilo-girls." And computing time was measured, in turn, in "girl hours" (with complex calculations requiring a certain amount of "kilo-girl-hours").