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
Les Janka in international affairs and the formulation of U.S. foreign and defense policy. A graduate of the University of Redlands, Janka received a master's degree in International Relations and Middle East Studies from the School of Advanced International Studies at Johns Hopkins University. Janka worked for the United States Information Agency from 1964 to 1968 and was Assistant Dean of the School of Advanced International Studies of Johns Hopkins University from 1968 to 1971, when he was appointed Special Assistant to Henry Kissinger on the National Security Council at the White House. Janka became Senior National Security Council Staff Member for