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, Contai Khejuri I and Khejuri II CD Blocks. It covers an area of 268.47 km with a population of 231,777. Janka, Contai Janka is a village, in Khejuri II CD Block in Contai subdivision of Purba Medinipur district in the state of West Bengal, India. Khejuri police station is located at Janka. The headquarters of Khejuri II CD Block are located at Janka. As per 2011 Census of India Janka had a total population of 2,804 of which 1,452 (52%) were males and 1,352 (48%) were females. Population below 6 years was 347. The total number of literates in Janka was