POWERHOUSE COLLECTION

Replica optical equipment of diffraction grating by Thomas Thorp

Object No. H10033

A diffraction grating is a plate engraved with a large number of fine parallel lines. They are used in spectroscopy to analyse the spectra of stars into their compound colours. Every element has a different signature spectrum, the spectroscope allows the observer to define what elements the object is composed of. Spectroscopy was first used in astronomy in the early 1860s. One of its first uses was to determine the elements that comprise the sun. Star spectroscopes can allow a user to determine the composition of a celestial object, its motion, density, and temperature. Henry Augustus Rowland (1848-1901) invented a ruling engine in 1882 that produced a grating of high resolution and accuracy. He was awarded the gold medal at the 1890 Paris Exhibition for the grating. His invention allowed him to re map the solar spectrum more accurately than had ever been done before. The Rowland gratings became the standard instruments for spectroscopic work throughout the world. Thomas Thorp developed his celluloid diffraction grating replicas, which he made from an original Rowland Grating, and brought high resolution spectroscopy within the reach of the amateur. This device was used at Sydney Observatory for demonstration purposes. It remains of national significance due to its pioneering role in Australian science and its association with Australia's earliest astronomers. Reference: Stuewer, R.H., 'Henry Rowland:the ruler of the grating', Physics World, July 2001, p.47. Gerard LeTurner, 19th Century Scientific Instruments, Sotheby Publications, 1983, pg 160 Written by Erika Dicker Assistant Curator, February 2008

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Summary

Object Statement

Optical equipment in storage box, diffraction grating, replica, glass / leatherette / metal / fabric, designed by Henry Augustus Rowland, Baltimore, Maryland, United States of America, 1882, made by Thomas Thorp, London, England, 1905-1915, used by Sydney Observatory, Sydney, New South Wales, Australia, c.1905-1950

Physical Description

Optical equipment in storage box, diffraction grating, glass / leatherette / metal / fabric, designed by Henry Augustus Rowland, Baltimore, Maryland, United States of America, 1882, made by Thomas Thorp, London, England, 1905-1915, used by Sydney Observatory, New South Wales, Australia, [1905-1950] Thorp's celluloid replica of the Rowland metal diffraction grating. The diffraction grating consists of a rectangular glass plate with a square grating etched in the centre.The grating has 14510 lines to the inch. There is a label glued above the grating and another adhered below the grating. The grating is enclosed in a leatherette case with a hinged lid. Observatory stock number 104.

PRODUCTION

Notes

Henry Augustus Rowland developed the metal diffraction grating in Baltimore Maryland, United States of America in 1882. This diffraction grating was made by Thomas Thorp between 1905 and 1915 in London, England.

HISTORY

Notes

The diffraction grating was used at Sydney Observatory for demonstration purposes between 1905-1950.

SOURCE

Credit Line

Source unknown

Acquisition Date

14 November 1983

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