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H9893 Mural circle, brass /stone / glass, designed and made by Edward Troughton, London, England, 1807-1809, used at Parramatta Observatory, Parramatta, New South Wales, Australia, 1815-1825. Click to enlarge.

Mural circle by Edward Troughton used at Parramatta Observatory

There are two main types of telescopes. One uses a curved reflecting mirror to capture an image of celestial bodies the other uses a refracting lens to gather the light. This mural circle was used in conjunction with a telescope and was set into a wall. It was then turned on an axle so the telescope could observe the stars as they passed through their meridian.

These are the remaining parts of the mural circle which arrived in Australia with Governor Brisbane in late 1821. They and presumably …


Object No.


Object Statement

Mural circle, brass /stone / glass, designed and made by Edward Troughton, London, England, 1807-1809, used at Parramatta Observatory, Parramatta, New South Wales, Australia, 1815-1825

Physical Description

A mural circle consisting of a flat brass ring with numbers engraved around the outside edge. The circle is divided into two, each half being numbered from 0-180. Accompanying the ring are seven hollow glass cylinders on circular metal bases and three cylindrical brass eyepieces. One of the eyepieces is fixed to a circular base that has been squared off to form a straight edge and one is fixed to a triangular brass stand. Also with the mural circle is a flat metal disc; a brass disc with a cylindrical footing in the centre; a solid brass ring with an inner ring attached permanently to the outer ring by four screws; and a solid grey stone disc with a hole in the centre. In addition there is another small brass disc with a lens in the centre. There is also a collection of 51 screws and assorted attachments including metal brackets and washers with the mural circle.



The mural circle was invented by Edward Troughton and made between 1815 and 1825 by Edward Troughton of London, England.

Cooke Troughton & Simms
In 1782 John Troughton purchased Benjamin Cole's shop in Fleet Street, London enabling him to sell his own signed products. His instrument making business supported several dynasties of Troughtons before becoming Troughton and Simms and later still Cooke Troughton & Simms. This firm was one of the most well respected firms of instrument makers of the 1800s.

While his brother enjoyed some early success, the business really expanded once Edward Troughton (1756-1835) took over the business in 1807. Edward and his brother John were both designers and manufacturers of instruments and the quality of their work won them contracts with the leading Government bodies of the time. These included The Royal Society, the Greenwich Royal Observatory, the Board of Longitude, the Board of Ordnance and the East India Company.

One of the main factors in the success of the business was the use of a dividing engine which could speed up the labourious process of marking the small divisions of measurement necessary for scientific instruments. This machine was based on that designed by Jesse Ramsden (1735-1800) which had won a prize from the British Board of Longitude in 1775. As a result of this the Board of Longitude was allowed to instruct Ramsden to allow up to ten other instrument makers to copy his machine. One of these was John Troughton and the new machines established both Ramsden's and Troughton's reputations. The dividing engine speeded up both accuracy and production and rather than spending 12 weeks, six days a week and eight hours a day graduating two meridian circles this machine enabled the same job to be completed in around 10 hours.

The workshop produced a broad range of instruments from large telescopes and theodolites through to smaller mathematical instruments. Before 1835 most of the optics appear to have been supplied by Dollond as Edward Troughton was reputed to be colour blind. It is also important to note that from the early years the precision engineering of castings and turnings of their instruments were mainly outsourced to Maudslay Field & Donkin or Ransome's & May.

One of Edward Troughton's apprentices, William Simms, was taken into partnership in 1826 and after Edward died in 1835, Simms became the manager of the establishment and the company became Troughton & Simms. Under Simms the company continued to expand and produced instruments for Britain and her colonies as well as for markets in Europe and America. When William Simms died in 1860 the estate was worth around £80,000. The company was next managed by William Simms (junior) and his cousin James who carried the firm into the industrial age.

During the 1860s they moved the company from Fleet St to two acres of land at Charlton on Woolwich Road and by 1866 the factory employed 61 men and 20 boys. For the 1874 transit of Venus, Troughton & Simms made only five transits and four portable azimuths but did refurbish some older telescopes lent for the occasion. Telescopes and transits of the period were often hybrids with the structure ordered from Grubb's or Troughton & Simms with lenses from Cooke.

However by 1887 the company was able to produce all the parts necessary for their instrument and the company employed nearly 200 people. James Simms died in 1915 and the company was turned into a limited liability company by his two sons William and James. Things however were not so easy for the two sons and in 1922 the business was bought out by their rival T. Cooke & Sons becoming Cooke, Troughton & Simms.



The mural circle was brought to Australia by Governor Brisbane to be used at the Parramatta Observatory.

Cite this Object


Mural circle by Edward Troughton used at Parramatta Observatory 2022, Museum of Applied Arts & Sciences, accessed 3 December 2022, <>


{{cite web |url= |title=Mural circle by Edward Troughton used at Parramatta Observatory |author=Museum of Applied Arts & Sciences |access-date=3 December 2022 |publisher=Museum of Applied Arts & Sciences, Australia}}


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