Rockwell scale Rockwell scale The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single letter, that use different loads or indenters. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale (see below). When testing metals, indentation hardness correlates linearly with tensile strength. This important relation permits economically important nondestructive testing of
Measuring the Universe Measuring the Universe Measuring the Universe is a performance art work by Slovak artist Roman Ondak first installed in the Pinakothek der Moderne in Munich in 2007. The exhibition stars as a blank white wall and begins to fill when museum guards mark visitors' height along with their name and the current date. It is in the collection of Tate Modern in London, Pinakother der Moderne in Munich and MoMa in New York. The only items required for the installation were a white room and a few black markers. What began as a clean white space has been filled with