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These 'computers' calculated ballistic trajectories by hand
PHILADELPHIA - One publicity photo of the Eniac is so famous that the Smithsonian's photo archivist knows its accession number by heart. It shows three women setting switches and inserting plugs. The photograph is obviously staged, and the women look like switchboard operators posed at boards. A man in the photograph-he also looks posed-is standing back and appears to be supervising them.
That image has haunted the women who worked on Eniac and has contributed to the misconception that they were little more than low-level technicians who set up the machine according to the instructions of others.
To understand their true role, a brief review of the Eniac's history and of developments just prior to World War II is necessary.
If you ever sweated over a differential equation, consider what it would feel like if one could save your life, not just your GPA. During both World War I and World War II, ballistic trajectories were calculated by hand. The results were an attempt to mathematically model every possible field condition while taking into account the weight and shape of the shells and their propellant charge. The data as compiled into firing tables, which field gunners would look upoften while under fire-to aim their weapons.
That worked fine when "the targets were being pulled by mules," observed Lt. Col. Herman H. Goldstine of the Ballistics Research Laboratory, who was a first lieutenant in World War I. But by World War II, the targets were airplanes, and the United States was creating guns that could fire at supersonic speeds.
To keep up, the army sought college-educated women to calculate trajectories. "Able-bodied men were all needed for the war; even Pres[per Eckert, co-inventor of the Eniac] had to get an exemption for essential work from the Secretary of War," said Kay Mauchly Antonelli, who was the secondwife of John Mauchly, the Eniac's other co-inventor. Mauchly Antonelliborn Kathleen McNulty-was recruited through "an ad that looked like a 'wanted' poster. It said, `Wanted: Women With Degrees in Mathematics.' " The starting annual salary of $1,620 was very good for the time, she said.
"We had to calculate where the bullet would be every tenth of a second, and just to find...