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
71 Harrington Street, The Rocks and working classes in residence in The Rocks between the 1890s and the mid 1970s. The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales. The retained section of the house has aesthetic significance as part of a strong visual precinct forming a characteristic Rocks townscape with the adjacent terraces and the Harbour Rocks Hotel on the other side of the street. The retained street section of the former house enhances the human scale of the streetscape and reinforces the historic character of The Rocks. The item meets this