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 Ahmed Janka Nabay Ahmed Janka Nabay (January 5, 1964 – April 2, 2018) was a Sierra Leonean musician and a major figure in Bubu Music, a traditionally Temne music which is played by up to 20 musicians blowing into bamboo pipes of different sizes. He first earned attention after performing for an audition of SuperSound. Janka Nabay recorded his album in Forensic Studios in Freetown during the Sierra Leonean Civil War. Since moving to Washington, D.C. in 2003, Janka Nabay has continued to play bubu music, including a performance at the CMJ College Music Marathon in New York in 2009