Go back to article: The life and material culture of Hertha Marks Ayrton (1854–1923): suffragette, physicist, mathematician and inventor

Dividing and conquering: Ayrton’s line-divider patent in 1884

Upon her return to London in the early 1880s, Ayrton supported herself by teaching and tutoring mathematics but also began to consider ways of earning a living including patenting her inventions. In March 1884, Ayrton was granted British patent 5543 Improvements in Mathematical Dividing Instruments for her line-divider, an engineering drawing instrument for dividing a line into any number of equal parts and for enlarging and reducing figures.[5] Ayrton had been inspired by the illustration of a drawing instrument made up of a series of parallelograms, provided to her by her cousin Ansel Leo in February 1883. Almost instantly, Ayrton saw the weaknesses in the idea and set about improving it in collaboration with her cousin. However, their joint work came to nothing and it was a new line-divider design, invented and designed solely by Ayrton, which resulted in her March 1884 British patent as well as her later US patent, granted in January 1885 (Sharp, 1926, p 107; Jaffé, 2003, pp 120–121).

Ayrton’s British patent application was financially supported by Lady Goldsmid and Bodichon, who together advanced her enough money to take out her British patent as well as foreign patents. A couple of months after receiving her British patent, Ayrton turned down an Easter trip abroad with Bodichon to take out foreign patents for her line divider, including an application for a US patent for the device. Now described as a ‘Draftsman’s Dividing Instrument’, it was filed on 3 May 1884 and granted on 6 January 1885.[6] Whether Ayrton exploited her US patent or not remains unknown.

Figure 3

Pen and ink illustration of a draftmans dividing instrument

Cover page of US Patent 310,450 'Draftsman’s Dividing Instrument', filed on 3 May 1884 and granted on 6 January 1885

The line-divider was Ayrton’s first major invention and, while its primary use was likely to be for artists for enlarging and diminishing images, it was also useful to architects and engineers and was afforded a favourable reception by artists, architects and engineers alike (James, 2010, p 107; Tattersall and McMurran, 1995). The line-divider received many positive reviews in the scientific press. A Nature review of the line divider in January 1885 concluded that it was ‘...a very handy instrument for architects, engineers and practical drawing...’ and a review in the Academy warmly observed that the line-divider was advantageous ‘to all those who have to do with the line and the rule’ (quoted in Sharp, 1926, p 108).[7] It would appear that one of the foreign patents applied for by Ayrton was French as the line-divider also received a good reception in the Paris-based periodical Revue Scientifique. On 14 May 1885 it noted that the instrument was invented by a Girtonian and concluded: ‘L’on a souvent prétendu que la femme n’est capable que d’assimilation et non d’invention: l’appareil que nous venons de décrire est une preuve mathématique du contraire.’ (‘It has often been asserted that women are only capable of assimilation and not of invention; the apparatus we have just described is a mathematical proof to the contrary’, quoted in Sharp, 1926, p 109; translation author’s own).

On 14 February 1885, Ayrton (credited as Sarah Marks) read a paper before the Physical Society entitled ‘The Uses of a Line-Divider’ which described the many uses of her patented line-divider and which was also re-printed in the Philosophical Magazine (Marks, 1885a; Marks, 1885b). Towards the end of her well-illustrated seven-page paper, Ayrton expanded upon the uses of the line-divider:

The divider would also be useful on board ships for drawing lines on charts parallel to other lines at some distance. It would be much better for this purpose than an ordinary parallel ruler on account of its very large range and capability of being fixed (Marks, 1885a, 7).

The device was manufactured and sold by W F Stanley and Company of Great Turnstile, Holborn, London, an engineer and specialist maker of scientific and mathematical instruments, and was available in three lengths: six, twelve and twenty-four inches in length.[8] The device was also shown at the Loan Exhibition of Women’s Industries held in Bristol from February to April 1885 and organised by Anglo-Irish suffragist Helen Blackburn.[9]

In the aftermath of the success of her line-divider and with increased confidence, Ayrton’s supporters suggested that she become an entrepreneur and start her own business as an inventor and manufacturer of mathematical instruments (Wynarczyk and Jaffé, 2011, p 11). Instead, Ayrton began to seriously consider a scientific career and, to this end, in 1884 she began to attend evening lectures four nights a week as a special student at Finsbury City and Guilds Technical College, the first technical college in England. Ayrton studied electro-technics (electricity and physics) at the college where she was just one of three women studying alongside 118 men (Jones, 2010). Here Ayrton was taught by physics expert, renowned electrical engineer, and FRS Professor William Edward (Will) Ayrton, then Professor of Applied Physics of the City and Guilds of London Institute, of which Finsbury Technical College was a subsidiary.[10] A year after they met, they were married on 6 May 1885 and another year later in 1886 they had a daughter, Barbara Bodichon, named after Ayrton’s mentor and supporter.

Ayrton’s new husband William Ayrton was a widower with a young daughter (Edith) and was very supportive of women’s education and legal rights. With marriage came relief from the financial worries that had plagued Ayrton’s early life and after settling down to married life, Ayrton resumed her scientific research working from a laboratory in the family home. In 1888, Ayrton began teaching classes on practical and domestic electricity to women but the combination of her domestic responsibilities and young daughter meant Ayrton had little time for further research and work.

In 1891, Ayrton’s mentor and her daughter’s namesake Barbara Bodichon died. Ayrton was greatly upset and grieved deeply for years afterwards but there was a positive outcome: Barbara left Ayrton a sum of money which enabled Ayrton to support her ageing mother and to hire a housekeeper so that she might dedicate more time and energy to her research. In the early 1890s, Ayrton began researching the properties of electric arcs. At first, she began by assisting her husband with his research but soon she took over the research herself.

Component DOI: http://dx.doi.org/10.15180/181002/003