Verity Allan

When conscripted workers returned to Cambridge after the Second World War, some of them brought with them knowledge of some of the technological advances in Radar and computing.

The histories of the Labs have focussed on the dynamic men who directed the work: Watson & Crick (and later Aaron Klug) at the MRC unit (initially part of the Cavendish), Mott in High Energy Physics, (HEP), Martin Ryle in the Astrophysics Group (AP), and Maurice Wilkes, Director of the Mathematical Laboratory. All of the scientists won Nobel Prizes, and much of their work was facilitated by computation, first done by people, later by computers.

And these computers were often women, hired as "Computors", or "Technical Officers"* if they were lucky, first to do calculations by hand, and later to write computer programs. There were other women employed in technical roles, as "Scanners" for looking at photographic plates for HEP, looking for the traces left by sub-atomic particles, as draughtswomen, drawing contour maps and other technical diagrams, and also some research students.

* This job title still exists in the University; I'm employed as a Technical Officer.

The employment of women as Computors was common: at NASA, human computors calculated orbital trajectories for the early space program*; the UK Met Office employed computers, as evidenced by this guide from 1916: https://twitter.com/verityallan/status/1164850561214296065 , some of whom were probably women; at the Royal Observatory in Edinburgh, computers calculated the position of stars from photographic plates.

* As made famous by the book and film, Hidden Figures.

In the Cavendish, three main groups hired Computors: crystallography, the MRC (before it was spun off into a separate organisation), and astrophysics. All three groups were doing work (x-ray crystallography or interferometry) that involved Fourier Transforms. Later, they programmed the computers to do data analysis using the Fast Fourier Transform. These computers were the computers designed by the (then) Mathematical Laboratory, and included EDSAC II and TITAN.

However, despite their essential contribution to data analysis, the Computors were not likely to feature on papers. Much of this was the convention of the time, and some of this was down to a group culture (in Astrophysics at least) that did not encourage elucidation of the computational methods used. Since many of the scientific "computers" were also women, there may also have been some level of gender bias.

Whatever the cause, Computors did not get authorships on papers, and only ralrely are listed in the Acknowledgements section. We can look at a paper from 1962 as an example: Ryle, M. and Neville, Ann C., A Radio Survey of the North Polar Region with a 4.5 Minute of Arc Pencil-beam System, Monthly Notices of the Royal Astronomical Society 1962: https://ui.adsabs.harvard.edu/link_gateway/1962MNRAS.125...39R/ADS_PDF

This paper is a seminal paper on earth-rotation aperture synthesis. It is a full practical demonstration of the technique, using the 178MHz telescope to collect the data, and the EDSAC II computer to process the data.

The electronic computer was essential - it would have taken too long to do the calculations by hand. Some of the program was written by Ann Neville, one of Martin Ryle's research students, and co-author on the paper. However, the paper also contains what may be the first reference to a practical Fast Fourier Transform, devised by David Wheeler of the Mathematical Laboratory.* This feat doesn't earn him an author credit, though; he just gets mentioned in the acknowledgements. This is something that today would certainly earn him a co-author credit, and then a ton of references when his work was used for other applications.

Also mentioned in the Acknowledgements was Mrs E Waldram, for the "photographic output". This actually involved some early work on computer graphics, to output the data on a CRT (Cathode Ray Tube) and then photograph that.

Not mentioned in the acknowledgements at all is the team of people known as "the girls in the attic". They did the work to draw the fantastic map of the North Polar region, joining several photographic plates together into a hand-drawn map. Until good printing of computer graphics was possible, the "girls in the attic" routinely produced contour maps and other technical drawings. Very rarely did they get credit in the acknowledgements. (They did get credited in at least one PhD thesis in the Astrophysics group, by a man who will remain nameless.)

* I'm trying to confirm that this is a version of the Fast Fourier Transform, rather than something similar but distinct. This is still a work in progress.

I have looked at papers primarily from the 1950s to 1970s - by the 1980s, the convention was changing, and Computers and Technical Officers were more likely to have substantial contributions recognised on papers. I have a list on ADS of the early papers from the Astrophysics Group, which I have used as a reference: https://ui.adsabs.harvard.edu/public-libraries/KkZ1AAqVRsakG7N87AKV2A

I am keen to find out more about these women, and the techniques they employed, especially the computing techniques used. I work on the Square Kilometre Array, which will produce huge amounts of data, and memory management is going to be important again. We may be able to reuse some of the insights from the limitations of early computers to improve software for cutting-edge science in the 2020s. As well as the computers, I'm looking at the female research students in the Radio Astronomy group, as women have been working in the field for a long time. We just don't know about most of them.