Inventor Professor Meredith Thring testing one of his invalid chairs by using it to climb stairs, at Queen Mary College in Stratford, London, November 23rd 1972. (Photo by Wesley/Keystone/Getty Images)
Inventor Professor Meredith Thring testing one of his invalid chairs by using it to climb stairs, at Queen Mary College in Stratford, London, November 23rd 1972. (Photo by Wesley/Keystone/Getty Images)