Imagine turning up for the practical examination of the SMC(Tech), say, and reading the following as the first task to perform: ‘Go outside and gather spiders, then return and extract their silk thread.’ In fact, these were the exact instructions given to Ken Bass, an optical technician, and other staff at a Leeds-based optical manufacturer during the early days of the Second World War. It is stretching things a little to say that those spiders won the Allies the war, but they certainly made an important contribution to the war effort.
What on earth could those arachnids have had to do with optical manufacturing? The story of the secret spiders, and how the unique property of their silk was used to great effect in the manufacture of gun-sights, only came to light in 2015 when Bass recounted the firm’s wartime exploits to the media.
Kershaw’s, the optical manufacturer who had begun making gun-sights and binoculars under Ministry of Defence contracts during the First World War, had hit upon the idea of using spider silk to solve a perennial problem relating to gun-sights that affected the accuracy of a range of weapons.
The traditional thin wire used as the cross-hairs in the gun-sight target graticule had a tendency to snap as a result of the vibrations caused by the firing of the weapon, thereby rendering it difficult subsequently to aim accurately. At the outbreak of the Second World War this was becoming a major concern.
The boffins at Kershaw’s realised that spider silk not only had great tensile strength, but could withstand vibrations better than wire; indeed, a spider relied on feeling the vibrations created by an insect landing on its web to be able to detect the presence of prey. Bass recalls that one particular species of large spider was identified by the firm’s scientists.
Although he doesn’t know its name, he remembers that staff were sent out onto the North Yorkshire Moors to gather specimens, which were then passed to him in matchboxes. The spiders were set to work by being encouraged to spin their webs across a wire frame. Once the silk threads had been harvested the spiders were returned to their natural habitat, their secret role in the war effort completed.
The lateral thinking that led to the use of spider silk for gun-sight cross-hairs is not entirely surprising given that Kershaw’s had long experience with military optical contracts and a flair for finding ways to get things done, sometimes with a degree of officially sanctioned subterfuge.
The founder of the optical business was Abraham Kershaw, born in 1861 near Bradford. He was apprenticed to an electrical instrument maker in Halifax, completing his apprenticeship by the age of 21. On his marriage certificate a year later he gave his occupation as ‘telegraph engineer’ but, in 1888, he moved to Leeds to start his own business as a scientific instrument maker and repairer.
Regarding a request for possible funding for the new project, Kershaw’s wife’s uncle is recorded by Kershaw’s younger son, Norman, as saying, ‘Nay it’s no use us both losing our brass, if you survive the first twelve months I’ll put some money in,’ which drew Kershaw’s response: ‘If I survive 12 months I will have no use for your money.’
Presumably the uncle’s money was not required as, by 1898, Kershaw had twice moved to larger premises and was now employing thirty people. The first government contracts came during the Boer War for specially-made portable telegraphic and heliographic signalling equipment. Meanwhile the firm branched out into optical and photographic instrumentation. Two patents taken out by Kershaw in 1904, a method for measuring shutter speed and a folding mirror mechanism, heralded the first single lens reflex camera.
His ‘Soho Reflex’ camera became the industry standard, with production of different versions continuing until 1952. No finer endorsement of the camera could be given than that of Herbert G Ponting, photographic officer to the British Antarctic Expedition, who used two of the instruments on Scott’s ill-fated South Pole expedition of 1910 and testified that, in 1925, ‘These cameras are today in just as serviceable condition as when they were first made, notwithstanding the vast amount of work they have done and the exceedingly trying conditions of climate to which they have been subjected.’ The same year that Scott’s Terra Nova had set sail for the Antarctic, Kershaw formed, with his son, Cecil, A Kershaw & Son Ltd, based in Leeds.
The new firm was commissioned to develop a new, reliable, cinema projector, which resulted in the ‘Kalee No1’ (‘Ka’ for Kershaw, Abraham and ‘lee’ for Leeds). The Kalee series, again, practically became the standard in its field for a period.
On the outbreak of the First World War, military contracts took over from civilian work. A major problem at the time was a lack of good quality prismatic binoculars. The Ministry of Munitions calculated that a thousand new pairs a week of 6x24 binoculars, complete with graticules for directing gunfire, were required; but the market was dominated by German firms, most notably Zeiss (Jena), with no British manufacturer able to produce more than a few dozen pairs per week. The situation was so dire that the government had to appeal to the public to donate binoculars.
Etched glaticules eventually replaced the need for silk thread
A Kershaw & Son were seen by the Ministry of Munitions as the ideal company to approach given their record of precision technical work for the military. An offer was made of financial backing to build a new plant and develop the necessary machinery to facilitate the desired production level of top quality binoculars.
A stroke of good fortune came with the realisation that Zeiss had a depot in Mill Hill, north London, which they used for repairs to, and a limited production and assembly of, prismatic binoculars. Kershaw’s managed to secure the services of key technical staff from the depot, including W Freeman, their optics expert. By 1917 Kershaw’s were producing around 800 pairs of prismatic binoculars per week.
That year also saw Cecil’s younger brother, Norman, join the firm, bringing on board more optical expertise after completing a condensed wartime lens design course at Imperial College, London.
It was Norman who, many years later when speaking to a local historian, finally cleared up a family mystery from the Second World War: more cloak-and-dagger stuff for the war effort. Cecil and he had used to talk of two German nephews who came to stay with Cecil and his wife in Harrogate during the war. These young men rarely went out and only had contact with the immediate Kershaw family.
Kershaw's Soho Reflex camera was the industry standard
What Norman revealed just before his death was that these men were actually engineers brought over from Germany to operate highly specialised German die-casting machinery that had been installed in the Kershaw factory at the start of the war. Once their work had been completed, the relevant government authorities reclassified them as Swiss nationals to enable them to return safely.
Abraham, who died in 1929, would have been proud of his sons. He had received an OBE for his military work in the first war. After the second war Kershaw’s returned to their cinema projectors and other instruments.
The projector side eventually became part of MGM, while other parts of the Kershaw group came under the control of the Rank Organisation. Kershaw optical technician, Ken Bass, went on to open his own business, Bass & Bligh, with a colleague. Their Leeds shop repaired optical equipent and sold ex-government optical stock; the business continues as a camera shop in Harrogate.
And what of the spiders? Their secret part in the war effort ended once technological advances enabled Kershaw’s to dispense with using wires in the gun-sights. Instead a process was developed that enabled accurate etching of the glass graticules. And so the creatures were retired quietly from active service to live out the rest of the war on the North Yorkshire Moors, their secret safe for the next 75 years.