Barcol hardness test the Barcol impressor was developed by Walter Colman as a hand-held, portable means of assessing the hardness of a material during World War II. The United States Army Air Corps required a hand-held method of checking the hardness of rivets due to concerns that aircraft could be sabotaged by replacing normal rivets with soft lead or wooden ones which would fail during flight. The impressor operates when the tip is pressed against the material in question. The hardness of the material determines how far the tip indents and this is transferred by a tension spring and lever to be read
Walter Janka Mann's novel of dynastic decline, Buddenbrooks, which was to be a collaboration between East Germany's DEFA and West German film companies. Another ambition, in pursuit of which he met Charlie Chaplin near the latter's home at Vevey in May 1954, was a DEFA film with Charlie Chaplin as the leading star. On 6 December 1956 Walter Janka was arrested on a charge of Counter-revolutionary conspiracy and held in the Berlin-Hohenschönhausen Remand Prison. By March 1957 he had become one of six men arrested and held in respect of the alleged conspiracy. Janka remained in the Berlin-Hohenschönhausen prison for more than