A sun diagonal for observing the sun

Made by Browning, John in London, England, c1880.

This sun diagonal was used at Sydney Observatory as part of a major international project aimed at mapping the stars. A sun diagonal is a device that allows users to directly view the sun in white light without causing injury to their eyes. The prism reflects only a small percentage of the sun’s light up through the eyepiece. Around 95 % of the light and heat are directed out through the bottom of the device.

The sun diagonal is commonly known as a ‘Herschel Wedge’. William Hershel (1738-1822)...


Object No.


Physical Description

Astronomical equipment, sun diagonal, Herschel Wedge, metal / glass, made by John Browning, London, England, 1875-1900, used at Sydney Observatory, New South Wales, Australia, [1900-1950]

A sun diagonal, also called a Herschell Wedge, used in direct optical observation of the sun. This diagonal has been fitted with an adaptor plate apparently so that it could be used with the astrograph sighting telescope.

Observatory stock number 107.



58 mm


70 mm



The sun diagonal was made circa 1880 by instrument maker John Browning of 68, The Strand, London, England.

John Browning (1835-1925) was a significant maker of scientific instruments in the 19th century. His father, William Browning, had been manufacturing scientific instruments since the late 1700s and John joined him when he came of age. John Browning took over sole ownership of this business in 1856.

Between 1856 and 1872 he acquired provisional patents for numerous instrument designs and received a prize at the 1862 International Exhibition in London for his temperature compensated aneroid barometer. He was also a keen astronomer and set about manufacturing affordable reflecting telescopes. He gained wide repute among the ophthalmic surgeons in London for his instruments.

He was specifically known as one of the 19th century's leading designers and manufacturers of spectroscopes. It is recorded that Browning was not satisfied with his products until he had confirmation from the customer that the instrument worked perfectly. He provided a custom-made spectroscope for famous photographer William Henry Fox Talbot (1800-1877) in 1865 . He also published the book 'How to Work with the Spectroscope' in 1878.

He was a member of several scientific groups such as The Microscopical Society of London, The Meteorological Society, The Royal Institution, and The Royal Astronomical Society.

Browning instruments were manufactured at 111 Minories in London from around 1765 until 1872. In 1872 the company moved premises to 63 Strand in London, and it was also recorded to have had a workshop at 6 Vine St, London.

John Browning Obituary, Monthly notices of the Royal Astronomical Society, Vol XC, No4, February, 1930
Webster's signature database.

Written by Erika Dicker
Assistant Curator, February, 2008.


Browning, John c1880



Sydney Observatory 1900-1950


Credit Line

Ex-Sydney Observatory, 1983

Acquisition Date

9 November 1983

Cite this Object


A sun diagonal for observing the sun 2018, Museum of Applied Arts & Sciences, accessed 19 November 2018, <https://ma.as/230591>


{{cite web |url=https://ma.as/230591 |title=A sun diagonal for observing the sun |author=Museum of Applied Arts & Sciences |access-date=19 November 2018 |publisher=Museum of Applied Arts & Sciences, Australia}}


This object record is currently incomplete. Other information may exist in a non-digital form. The Museum continues to update and add new research to collection records.

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