A very rare example of an Ellwood’s air chamber helmet. (Collection of Roland Gruschka)

Stuart Bates’ article on “Ellwood’s Air Chamber Helmet” from July 5th 2012 describes Ellwood´s patent for a hat suitable for tropical regions. Whatever the shape – the idea is always executed in the same way. There are two shells that do not meet and form an “air chamber” – ventilated by holes or not – where the air is used as isolation against heat. Theoretically, a fine idea – but, as Stuart notes correctly: “There is no provision for the escape of heat, emanating from the wearer’s head, out of the inner shell which must have lessened the overall effectiveness of the design.” Ellwood´s must have had the same thought and here is an example of an Ellwood helmet where their own patent is altered. Continue reading →