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
Janka Bryl Janka Bryl Janka (Yanka) Bryl (, August 4, 1917 – July 25, 2006) was a Belarusian writer best known for his short stories. He was one of the older generation of Soviet writers who had begun their literary careers in Stalin's time but received a new lease on life in the late 1950s along with such contemporaries as Ivan Shamiakin and Ivan Melezh. His father was a railway worker. In 1922, his family returned to their hometown of Zagorje, which was then in Poland. He was unable to complete his education, due to financial difficulties. In 1939, he was drafted