Math­e­mat­ics for Bal­lis­tics Cal­cu­la­tors, Feb­ru­ary, 1943, US Army Photograph

I’m fas­ci­nat­ed by secrets. Who guards them? What are the stakes for reveal­ing them? My first young adult nov­el, The Poet­ry of Secrets, was about cryp­to-Jews dur­ing the Span­ish Inqui­si­tion. For them, keep­ing a secret was a mat­ter of survival. 

Then, while search­ing for inspi­ra­tion for my sopho­more nov­el, Tra­jec­to­ry, I came across a lit­tle-known group of women dur­ing World War II who helped lead the US Army to vic­to­ry by doing some­thing that was clas­si­fied. For them, keep­ing a secret was a mat­ter of duty. When I dis­cov­ered that many of those women were Jew­ish, I knew I had to bring their sto­ry to light. 

The year was 1942, sev­en months after the inva­sion of Pearl Har­bor. Ten young women in sen­si­ble heels, skirts, and cardi­gans walked down a path on the Uni­ver­si­ty of Penn­syl­va­nia cam­pus. They were between the ages of sev­en­teen and twen­ty-five, but they weren’t coeds. Nor were they sec­re­taries or nurs­es or teach­ers which was the only career option for women at that time. Their des­ti­na­tion: an emp­ty fra­ter­ni­ty house tak­en over by the Moore School of Engineering. 

Out of the ten women, one was Black and nine were white. Two were iden­ti­cal twins. Five were Jew­ish. They hailed from var­i­ous cities across the North­east. And what they all had in com­mon was their skill with num­bers. These women were part of the Philadel­phia Com­put­ing Sec­tion (PCS). And they were the last of the human Computers. 

The term Com­put­er” was first used in the 1600’s to describe men who tracked time with cal­en­dars. In the 1860’s, a female astronomer named Maria Mitchell was con­duct­ing an offi­cial US Coastal sur­vey and called the peo­ple who worked for her, Com­put­ers. Then, in 1942, the US Army found them­selves with a prob­lem. They were over­whelmed by all the new weapon­ry that need­ed test­ing. Since the first world war, Aberdeen Prov­ing Ground in Mary­land had been con­duct­ing bal­lis­tics research with Com­put­ers, men who man­u­al­ly cal­cu­lat­ed the tra­jec­to­ry of a pro­jec­tile. But now with most men enlist­ed, it was hard to find enough civil­ian men with math­e­mat­i­cal back­grounds. The solu­tion? Get females to do the job. 

So the army con­tract­ed with the Uni­ver­si­ty of Penn­syl­va­nia, cre­at­ing a satel­lite research hub at the Moore School of Engi­neer­ing. The Junior Com­put­ers they recruit­ed would be doing advanced math. The only caveat: they couldn’t tell a soul what they were doing.

In war­fare, accu­ra­cy is cru­cial. Some­thing I learned while writ­ing this book was that gun­ners don’t just shoot at ran­dom. Fir­ing tables are need­ed so sol­diers know where the pro­jec­tile will land. This is done using iter­a­tive approx­i­ma­tions, a method of cal­cu­lus. The arc of a bul­let, mis­sile, or shell is mea­sured at mul­ti­ple points along its tra­jec­to­ry, tak­ing into account such fac­tors as dis­tance, alti­tude, wind, angu­lar veloc­i­ty of the earth, lat­i­tude, azimuth, rel­a­tive veloc­i­ty of sound, air den­si­ty, drag func­tion, and mass and diam­e­ter of projectile.

It’s painstak­ing and com­plex work. And the women rose to the task. 

Though they were well com­pen­sat­ed, their shifts could last up to six­teen hours a day. A typ­i­cal shell tra­jec­to­ry involved thou­sands of indi­vid­ual cal­cu­la­tions. It took up to forty hours to man­u­al­ly cal­cu­late just one six­ty-sec­ond bal­lis­tic tra­jec­to­ry. And because the types of artillery were con­stant­ly chang­ing, the women often had to throw out an entire week’s work. Their wrists were sore, their backs seized up, their heads pound­ed from the click­ing and clack­ing of the desk­top cal­cu­la­tors. Dur­ing the sum­mer, salt tablets were on hand to pre­vent dehydration.

It wasn’t all toil, though. They did man­age to have fun, going danc­ing at the Stage Door Can­teen, pic­nick­ing near the Schuylkill Riv­er, and explor­ing museums. 

Of course, not all one hun­dred mem­bers of the PCS were Jew­ish. But I want­ed to tell the sto­ry of those who may have had oth­er rea­sons to keep a secret, ones that went beyond duty. Those who want­ed to do some­thing, any­thing, to help their fel­low Jews in Europe who were being forced into ghet­tos and gassed in such large num­bers that many in Amer­i­ca didn’t believe it was even happening. 

With­out the skills of these math­e­mati­cians, the Allies may not have won the war. Below is a snap­shot of a few of these real-life Jew­ish women who were Computers. 

There was Adele Katz Gold­s­tine (not pic­tured), a fast-talk­ing Brook­lynite who smoked a pack a day. As Senior Com­put­er, Adele was the main recruiter for PCS. She held a mas­ters in math from Uni­ver­si­ty of Michi­gan and edu­cat­ed dozens of young women in grad­u­ate-lev­el numer­i­cal analy­sis for tra­jec­to­ry cal­cu­la­tions. She also wrote the tech­ni­cal man­u­al for the first dig­i­tal numer­i­cal com­put­er, ENIAC

The third floor PCS girls 

Doris and Shirley Blum­berg were iden­ti­cal twins. Recruit­ed from the pres­ti­gious pub­lic school, Philadel­phia High School for Girls, they were shin­ing stars of the math club. Their moth­er vol­un­teered for Jew­ish char­i­ta­ble orga­ni­za­tions, and though she didn’t go to school past eighth grade, she told her daugh­ters, You can’t make it in this world with­out an edu­ca­tion. I didn’t have the oppor­tu­ni­ty, but you do.” 

Marlyn Wescoff grad­u­at­ed high school at age six­teen, then entered Tem­ple Uni­ver­si­ty teacher’s col­lege. Although her fam­i­ly strug­gled for mon­ey (Marlyn owned a total of two dress­es and while one was being washed, she wore the oth­er), they lis­tened to music, read books, and talked pol­i­tics at the din­ner table every night. At grad­u­a­tion, the dean of Tem­ple Uni­ver­si­ty warned the Jew­ish stu­dents, Don’t look for any jobs in the sub­urbs. No one will hire you. Stay in Philadel­phia or Pitts­burgh.” Marlyn didn’t want to be a teacher. She knew how to work an adding machine and got a job crunch­ing num­bers at the Moore School before she became a Junior Computer.

Ruth Lichterman’s par­ents were Russ­ian immi­grants. Her father was a Hebrew school teacher. She attend­ed Hunter Col­lege, hop­ing to major in math. Dur­ing her first sum­mer after fresh­man year, she planned to take a wait­ress­ing job at Camp Copake in New York, an adult sum­mer camp for young Jews in the city. But then she saw the recruit­ment ad for PCS in her local paper.

Glo­ria Gor­don worked at the Brook­lyn Navy Yard in ship con­struc­tion and then moved to Philadel­phia where she got a job at the Moore School. Lat­er, she joined the pro­gram­ming team of the ENI­AC. In 1947, she trans­ferred to Aberdeen Prov­ing Ground to work on anoth­er secret project which may or may not have been part of the Man­hat­tan Project. 

The Junior Com­put­ers in my book, Tra­jec­to­ry, are fic­tion­al amal­ga­ma­tions of these women. And because I love secrets so much, I decid­ed to give one Com­put­er, our hero­ine Eleanor, a sec­ond secret, besides the clas­si­fied one. 

You’ll just have to read the book to dis­cov­er it.

Numer­i­cal Analy­sis for Bal­lis­tics Com­put­ers, Feb­ru­ary 1943, US Army Photograph

Cam­bria Gor­don is the author of The Poet­ry of Secrets, which Ruta Sepetys called an epic, poet­ic jour­ney,” and coau­thor of the award-win­ning The Down-to-Earth Guide to Glob­al Warm­ing, win­ner of the Nation­al Green Earth Book Award. Cam­bria has writ­ten for Los Ange­les Times Mag­a­zine, Boys’ Life, Par­ent Guide News, and The Jew­ish Jour­nal of Los Ange­les. She lives in LA with her hus­band and youngest son, and as close as pos­si­ble to her two adult chil­dren, with­out annoy­ing them.