Forgotten women in science: The Harvard Computers
In the first of a three-part series, Zing Tsjeng looks at the neglected contributions of female scientists through history.
The era of human computers didn’t begin with the West Computers or the Bletchleyettes. Toward the end of the 19th century, Harvard College Observatory drafted in dozens of women to take on one of the most unique mathematical computing jobs in its 178-year history: to unravel the mysteries of the heavens by calculating the positions of the stars.
The work was less glamorous than it sounded. Thanks to new photographic technology, astronomers were able to capture images of the night sky onto glass plates. The problem, however, was that there was far too much data and too few people to analyse it.
Observatory director Edward Charles Pickering (1846–1919) had an unusual solution: he employed a team of women to do it.
At the time, bright and talented graduates were emerging from America’s newly founded women’s colleges – such as Vassar College in upstate New York – and on the hunt for employment prospects that offered a little more excitement than working as a schoolteacher or running a household. Being a computer was as good as it got, even if they were paid far less than their male colleagues at 25 to 30 cents an hour. But it wasn’t just middle-class educated women who were offered a chance at classifying the stars; there were also uneducated women like Williamina Fleming (1857–1911), a Dundee-born single mother and housemaid whose aptitude for computing led Pickering to promote her from cleaning his rooms to computing his plates.
The Harvard Computers (1881–1919) – or, as they more rudely began to be known at the time, Pickering’s Harem – worked in the library next to the observatory. The process of measuring the brightness of the stars and their positions in the sky required painstaking attention to detail and utmost concentration. Though the work was considered boring and tedious – hence why women were landed with it – it was also a lot less straightforward than it seemed.
Most plates simply revealed dark splodges of dots against the glass. With the careful application of mathematical formulae, the women could work out the coordinates of the stars and their brightness. The northern and southern skies had never been mapped in their entirety before. The Harvard College Observatory, with its immense collection of plates, stood the best chance of doing it, and it couldn’t have made any progress without its computers.
Then came another challenge: how should they categorise these celestial bodies? Wellesley College graduate Annie Jump Cannon (1863–1941) created the Harvard Classification Scheme, which sorts the stars based on qualities such as their colour and temperature. As Cannon put it: “It was almost as if the distant stars had really acquired speech, and were able to tell of their constitution and physical condition.”
Her system is still used by astronomers today.
Cannon and another computer, Henrietta Swan Leavitt (1868–1921), were both deaf; in Cannon’s case, this proved advantageous when she wanted to concentrate at work, as she would simply remove her hearing aid to block out the noises of the outside world.
Even though none of them – barring Cannon – were ever allowed to use the mighty Harvard telescope known as the Great Refractor, the computers were on the cutting edge of astronomical discovery.
Fleming, for instance, catalogued more than 10,000 stars and from earth. However, initial publications of the finding missed out her name completely. (Subsequent catalogues, thankfully, rectified the mistake.) In 1899 she became the Curator of astronomical photographs and was one of the few computers to be appointed to a professional position at Harvard.
Leavitt, on the other hand, realised that some stars pulsate with consistent brightness, making these so-called Cepheid variables solid benchmarks for calculating distances across space: a method that Edwin Hubble relied on to prove that the universe goes beyond our own paltry galaxy. In this way, the findings made by the Harvard Computers were truly revolutionary.
Harvard continued to use photographic plates until the 1990s, when digital cameras supplanted the old way of doing things. But the 500,000 glass plates that the computers once pored over still reside at the university, along with 118 boxes of notes and logbooks recently unearthed by the curator of the Harvard-Smithsonian Centre for Astrophysics.
Together, they constitute a perfect record of what the night sky looked like a century ago, and of the women who sat in the small room next to Harvard’s telescope, deciphering the secrets of the universe. In 2005 the Centre began cleaning and digitising each glass plate for its archive. At the time of writing, more than 207,000 images have been preserved.
This is an extract from Forgotten Women: The Scientists by Zing Tsjeng. Published by Hachette Australia, RRP $27.99.