Go back to article: The life and material culture of Hertha Marks Ayrton (1854–1923): suffragette, physicist, mathematician and inventor
Quite a flap: the development of the 'Ayrton anti-gas fan' during the First World War
© Imperial War Museum
Left: Ayrton anti-gas fan
Right: Illustration of Ayrton fan in use, source unknown
After the German Army first used poison gas at the Second Battle of Ypres in April 1915, many British scientists quickly began to adapt their research to counteracting this new and deadly weapon. In early May 1915 and shortly after the news of German use of gas had reached England, Ayrton presented a paper on differences in pressure near obstacles in moving water and began to consider how this might have practical application in terms of removing gas from the trenches (Ayrton, 1915). She described her device, a fan which became known as the ‘Ayrton anti-gas fan’ in detail in a paper before the Royal Society in 1919. The fan provided an obstacle which created a vortex of air and pushed poisonous gas out of the trenches and back towards the enemy (Ayrton, 1919). Ayrton’s anti-gas fan was simple and consisted of a sheet of waterproof canvas supported and stiffened by a frame of cane and held by a hickory handle. At first, Ayrton tested the principle of the idea through experiments with burning brown paper in her drawing room laboratory; by mid-May 1915 she had developed a working model which she tested out in her friend and fellow suffragette Ernestine Mill’s back garden in Kensington (Crawford, 2000, p 23).
The War Office initially dismissed her invention and passionate exchanges were made publicly in the press until May 1916 when the War Office relented and granted Ayrton the opportunity to demonstrate the device. An assistant and one of her colleagues from the Central College, a Mr Greenslade, organised tests of the fans and trained soldiers in how to use them (Ayrton, 1919, p 256). Meanwhile, Ayrton herself arranged their production. Initial examples made in 1916 had severe operational limitations: they were only effective in winds less than nine miles an hour and had to be operated manually. By 1917 Ayrton’s adapted version of the fan, now mechanically operated and resistant to high winds, was ready but Ayrton faced continued opposition from the War Office as well as bureaucratic delays. However, with the support of A P Trotter, a fellow electrical engineer and member of the IEE who had contacts in British military command, the Ayrton anti-gas fan was soon being used on the Western Front with an eventual total order of 104,000 fans (Hirsch, 2009). Ayrton anti-gas fans were used to clear trenches, dug-outs and shell holes, and mine craters of poisonous gases.
In 1920 and possibly in advance of submitting a claim to the Royal Commission on Awards to Inventors (RCAI) for financial compensation for her ‘Ayrton anti-gas fans’, Ayrton described her invention and its development in The Times and complained about official apathy to her and others' scientific endeavours and the delay in supplying her device to frontline troops:
On May 6, 1915, I conceived the idea that it might be possible for our men to drive off poisonous gases and bring in fresh air from behind by simply giving impulses to air with hand fans. By May 14, I had made a small model, giving surprisingly good results, and I wrote to the only authority at the War Office I knew at all, to offer it to the army.
The day after Ayrton’s article was published, a letter of support from Major H J Gillespie, formerly of the Royal Field Artillery, who had introduced the Ayrton anti-gas fan into the Army and onto the Western Front was published. This praised the invention and noted the time it took the Army and War Office to evaluate, manufacture, and then introduce such devices onto the frontline. A few days later on 6 May 1920, one Major Sisson, formerly of the Royal Engineers, wrote to The Times observing that responsibility for turning down the Ayrton anti-gas fan lay with the British Army in France and not the War Office: ‘the fans were given up because prolonged experience in the field showed that they served no useful purpose for defence against gas.’ The debate, albeit limited, surrounding the Ayrton fan may have led Ayrton not to submit a claim to the Royal Commission on Awards to Inventors (RCAI), founded to allocate credit and some compensation for wartime technical innovation and contribution. Instead, Ayrton’s sole claim to the RCAI was for the Admiralty’s use of her negative carbon searchlight arc system; the claim was not completed until after Ayrton’s death in August 1923 and so the final claim in 1924 was made by Ayrton’s Executrix, her daughter Barbara Ayrton Gould.
Nonetheless, Ayrton continued to work in the field of vortex studies until her death in August 1923: one of two partially-filled research notebooks on Ayrton anti-gas fans contains notes on final experiments conducted in early June 1923. The second notebook entitled ‘Thoughts on Fans’ is barely filled and seems to have been abandoned sometime in late 1918, most probably after war had ended. Meanwhile a notebook begun earlier – in July 1918 – on using motor-driven fans to apply the ‘Flapper Principle’ to tubes reveals the practical application to which Ayrton wished to apply the Ayrton anti-gas fan in the post-war years. To this end, Ayrton anti-gas fans were later adapted to improve ventilation in mines, sewers and industrial sectors.
Component DOI: http://dx.doi.org/10.15180/181002/005