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Hardness Comparator - 'Star Turn', London, circa 1920s Object Reg. No: ST 044579

Summary:
"Star Turn" surface hardness comparator in bakelite case. Used to measure the hardness of materials as measured in the Rockwell C scale.

The measurement is made by rubbing pins across materials, until one pin scratches and one slides; the hardness of the material is the measurement between the two pins.
Description:
Consists of 9 steel spikes radiating from a bakelite base. Marked from 46 to 62 on each face of bakelite base. Base has star motif at centre. Bakelite cover is labelled "STAR TURN" with star motif in centre, and 9 lines radiating outwards. Registration number has not been painted on object
See also Trade Literature.
Acquisition Information:
Donation from Melbourne Observatory
Discipline: Technology
Dimensions: 2.5 cm (Height), 6.5 cm (Diameter)

More information

Tagged with: hardness comparators, iron steel making, physical apparatus instruments
Themes this item is part of: Melbourne Observatory Collection, Science & Measurement Collection, Positional Astronomy at Melbourne Observatory, Weights & Measures at Melbourne Observatory, Melbourne Observatory & Standard Time in Victoria, Astrographic Catalogue, Transits of Venus, 1874 & 1882, Buildings at Melbourne Observatory, Star Observations & Personal Equation, Meteorology at Melbourne Observatory, 1863-1908, Melbourne Observatory, 1863-1944, Geodetic Survey of Victoria, 1858-1872
Primary Classification: ASTRONOMY
Secondary Classification: Research
Tertiary Classification: laboratory instruments
Manufacturer: Star Turn, London, Middlesex, England, Great Britain, circa 1920s
User: Melbourne Observatory, South Yarra, Victoria, Australia

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