Merran Williams

Today is International Day of Women and Girls in Science so let’s celebrate one of the earliest. Woman of the Day Mary Edwards (1750-1815) of Ludlow, Shropshire, the first ever woman to work as a human computer for the British Nautical Almanac and the first to be paid by the Board of Longitude. All of this at a time when ships navigators depended on establishing longitude by calculating the difference between the time aboard ship, which they could check by the sun, and the time at Greenwich. Every hour’s difference is equivalent to 15 degrees longitude. John Harrison’s chronometers were available but extremely expensive so John Maskelyne, the fifth Astronomer Royal, began publishing cheaper but extremely accurate almanacs. They were crucial to the Royal Navy and to shipping. Mary’s husband John took on piecework as a computer for the Nautical Almanac to supplement his meagre income as a curate. He had a family and an expensive hobby to support - making telescopes. In fact, he was far more interested in his telescopes than he was in theology or calculations but he committed to providing the long, boring calculations needed in return for payment for each six months’ work on each almanac from 1773 until his death in 1784. You might wonder how he did it. Simple. Mary did all of the work. For every entry in a table, she had to look at up to twelve figures in astronomical tables and perform 14 operations on the data, repeating the whole process for every day of the month. It was boring, repetitive, but crucial work - lives depended on it - but she was very quick and very accurate. When John died at the age of 36 - he accidentally inhaled arsenic while messing about with his telescopes - his widow was left with two children, a pile of debts and notice to quit their home. Mary wrote to Maskelyne to ask if she could continue her work because she needed the money. The Edwards were personally acquainted with Maskelyne and he almost certainly knew of the deception but at that time, it was unheard-of for a woman to occupy an academic government-funded position. He agreed that she could take over the role officially, full time, and be paid directly by the Board of Longitude. To support her family, Mary took on more and more work until eventually, she was computing a whole year’s worth of tables. Other human computers took several months to deliver two months of tables. She could do it in three or four weeks. Ironically, Ludlow is landlocked - and yet here was Mary, keeping sailors safe. Her reputation for reliability and accuracy proved to be her greatest asset. Once the Board of Longitude had ten years’ worth of tables in hand, it halted the work. Mary asked for compensation for lost income and got it. When the work started again, she was back on the payroll. In 1811, when Maskelyne died and a new Astronomer Royal was appointed, the work slowed to a trickle. Again, she petitioned the Board and again they stepped in to protect her livelihood. Mary was simply the best human computer they had. She worked until her death in 1815 at the age of 65. Mary’s daughter Eliza also worked as a computer, initially helping from a young age and then independently after her mother died. She continued to work for the Nautical Almanac until 1832, when computing work was centralised in London and there was no place for women employees in the new HM Nautical Almanac Office. Civil Service rules made the employment of women very difficult. The minor planet 12627 Maryedwards in the Asteroid Belt is named in Mary’s honour. I couldn’t find an image of Mary but here is the blue plaque at 4 Brand Lane, Ludlow, where she lived. Brava, Mary.