- Historic Sites
In a top-secret program, talented, young female mathematicians calculated the artillery and bomb trajectories that American GIs used to win World War II
Fall 2011 | Volume 61, Issue 2
For young women in the 1940s with a love of math and science, the PCS work represented an unparalleled opportunity. "If we went out and tried to get some other job between high school and college, it would be a dull kind of a thing, so we may as well go into something that is interesting," Doris said.
Under the direction of Capt. Herman Goldstine, the research lab mathematician in charge of the PCS, the Army brought scores of young women to the university, mostly from the Philadelphia and Baltimore area at first but later from New York, New England, and the Midwest. The recruits dove right in, learning the specialized mathematical differentiation and integration techniques involved in ballistics calculations.
"It's advanced mathematics," Shirley Blumberg explained. "Equations were solved in order to figure out the trajectory of a bullet or a bomb; just exactly where it started; what the muzzle velocity was of whatever was shooting this bullet; and where it was going. We knew the distance, and we had to figure out how it was going to get there, exactly where it had to land. The differential equations were part of the solution of the trajectory... We knew that's what we were hired to do, to create this book that was going to be distributed to the guys who were shooting the guns. They were going to use these tables to figure out how to hit a particular target." Goldstine's wife, Adele, also a gifted mathematician, was among the instructors, as was Mary Mauchly, married to Moore School professor John Mauchly—who would soon help initiate another secret war project.
Working out of a former factory and neighboring fraternity house, the women would be given different assignments to create the table for a particular weapon," explained LeAnn Erickson, a filmmaker who details the story in a documentary. They were well paid, particularly given the era and their gender. The long hours (they sometimes worked two eight-hour shifts) and the sense of shared purpose helped the women bond. During their off hours, they picnicked and went to dances and movies; some dated whatever men were left behind by the war.
Wartime secrecy regulations required that their superiors tell the Rosies little beyond the minimum necessary to do their jobs. "We did not know where these tables were going to be used," Shirley said. "We knew that they were going to be used in Europe, but we had no idea exactly where. We found out later, when we read the newspapers, where the big battle was. And we realized that some of the information—maybe all of the information they had on the tables—we developed in our office." They understood, of course, that their calculations would be used ultimately to kill other human beings, but most didn't dwell on any moral qualms until much later. Occasionally, though, they could- n't help but consider the realities of their work. One such occasion occurred in spring 1944 after the bloody landings at Anzio, Italy, during which the Allies attempted to capture Rome by outflanking German forces with an amphibious attack.
"We had some big shots in Washington come up in military uniforms to give us an award," Shirley recalled. "They came in and stopped our working and said there was a presentation to be made. And this general got up there and told us how valuable our work is, and we were doing such a great job for the war effort... and that the landing on the beach at Anzio was a great success. And therefore, we're getting this big award for doing that wonderful work that made it such a success." For Shirley and most of her co-workers, it was merely a distraction: "We were in the middle of working. Let us finish what we're doing." Later, however, she had second thoughts. "When I read about the bloodbath on the Anzio beaches in the newspapers, I got physically ill."
Doris had a similar experience when the Rosies were asked to create data for the invasion of Guam, where Japanese troops "were in trenches all around the island." She recalled discussions with their supervisors about different formulas to be used for computing shell trajectories depending on whether a Japanese soldier was standing or was lying flat in a trench or on the ground. "That kind of got to me... because it made it more personal. I thought, 'My god, what are we doing here?'"
The work continued, even after V-E Day saw the Rosies dancing in celebration in the gardens on the Penn campus. John Mauchly and J. Presper Eckert were already secretly setting the stage for the first great leap beyond human computers and mechanical differential analyzers to the first electronic computer: the Electronic Numerical Integrator and Computer, or ENIAC.
The women heard rumors about an interesting project at the Moore School, but they didn't know any details. "We knew that these two guys were in this room right off the differential analyzer room, and that they were inventing something," Shirley recalled. "But we had no idea what they were inventing until much later. They invited a couple of us in there and said, 'Do you wanna see something?' They had this great big machine up against a wall and lots of lights and wires coming to it. And they took us in, and we said, 'What's that?' And they said, 'That's going to be the first electronic computer. That's going to do the work that you're doing in seconds.' We said, 'Yeah, go dream on, you crazy guys.'"