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
Ahmed Janka Nabay and 2010. In June 2010, he formed a full band, Janka Nabay and the Bubu Gang, with members of four Brooklyn indie rock groups Skeletons, Gang Gang Dance, and Starring. In 2012, Janka's band announced that they had signed a three-album record deal with David Byrne's record label, Luaka Bop. Janka Nabay was of Mandingo and Temne descent, two of the ethnic groups within Sierra Leone. It was reported on April 2, 2018 that Janka Nabay had died. Causes of his death remain yet unknown. He was 54 years old. "Ahmed Janka Nabay, the Sierra Leonian musician renowned for pioneering