The three chairs shown here might reflect a mixture of these principles with the top picture showing the famous 'Rietveld' design of 1918.  It had only been in 1912 that a researcher at the Firth-Brown laboratories in Sheffield had 'discovered' the useful properties of chromium in steels. During the First World war of 1914-1918 Stainless and chromium steels were being used and by 1925, the date of the Marcel Breuer design, the material was finding its way into new innovative products. The development of plastics occurred throughout the 1950's and 1960's ( and of course is still going on now as new qualities are demanded by new needs.. ) New techniques of manufacturing are developed as new materials emerge and the 'injection-moulded' plastic chairs shown in the third picture demonstrate how the availability of new materials and processes lead to new 'fashionable' products. Small changes in products and materials ('incremental') frequently go with 'market-

And what about the typewriter.  Before computers transformed our ability to change text and print out text (let alone e-mail) to friends and business customers the typewriter was used by armies of 'typists'. Copies were produced using a flimsy carbon-backed paper that carried an imprint of the hard keys as the keys onto a second sheet of paper beneath the paper being printed.  Errors were therefore something that couldn't be easily changed and the ability to spell was very important.  Perhaps the most interesting 'left-over' of the era

of the typewriter is the QWERTY layout of the modern keyboard.  Designed as it is so that the most commonly used keys were not placed together so that the mechanical keys didn't jam during the typing.