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
145 George Street, The Rocks group as a whole, contributes to a precinct unique to NSW with its historic associations and streetscape character. The group is an important part of The Rocks Heritage Conservation Area being sympathetic in scale and character and an extension of the remaining earlier buildings of George St, presenting a unified streetscape. The buildings are tangible evidence of the redevelopment of The Rocks in the last decade of the 19th century and first decade of the 20th century. 145 George Street has high social significance as a contributory element associated with the historic character of The Rocks, which is held in