Optical instrument, astronomical star diagonal, metal / glass, used by Sydney Observatory, made by T Cook and Sons Limited, England, 1897-1922
In 1874, after two years of inquiries, the NSW Government Astronomer H. C. Russell acquired a number of new instruments in preparation for the upcoming Transit of Venus. One of these was a new 11.4 inch telescope (H9886) purchased for the observation of double stars from the optician and instrument maker, Hugo Schroeder.
In 1870 Schroeder had made an objective for the Hamburg Observatory and the success of this instrument may have been one reason Russell sought him out. As well as the telescope Russell purchased some additional instruments from Schroeder for use with the telescope. These were a solar polarising eyepiece (H10380) designed for viewing the sun, a filar micrometer mounted on a graduated circuit (H10007), eyepieces (H10294).
This sun diagonal used in conjunction with the Schroeder telescope was purchased separately. The sun diagonal was attached to the view end of the telescope and allowed for the dissipation of heat caused by the magnification of the suns rays.
In the nineteenth century Cooke & Sons Ltd established a reputation as one of the most reputable optical instruments makers in Britain. Thomas Cooke started his business in York in 1837 and by 1855 had established his reputation as a maker of fine lenses for telescopes by winning a First Class medal for his 7 1/4-inch equatorial telescope. In 1860 he was commissioned by Queen Victoria's husband Prince Albert to construct a telescope for Osborne House in the Isle of Wight. The quality of their work was such that a lens and mounting completed in 1871 was still being used at the Cambridge University in the 1950s.
In 1879 some time after the death of Thomas Cooke in 1868 the firm was taken over by his sons Thomas (Jnr.) and Charles. The firm continued to supply many British Government institutions including the Admiralty, the War Office, Board of Works, and the Post Office. In 1894 Frederick retired from the business which was taken over by the Director Alfred Taylor and in 1897 it was reformed as a limited liability company. In 1922 T. Cooke & Sons brought out their rivals Troughton and Simms becoming Cooke, Troughton & Simms.
Todd, David, P., Stars and Telescopes, Sampson Low, Marston, and Co., 1900
Chaldecott, J., 'Printed Ephemera of Some Nineteenth Century Instrument Makers', in Blondel, C., Parot, F., Turner, A., Williams, M., (eds), Studies in the History of Scientific Instruments, Rogers Turner Books, London, 1989
King, H., C., The History of the Telescope, Dover Publications, New York, 1955
McConnell, A., Instrument Makers to the World; a History of Cooke, Troughton and Simms, William Sessions, York, England, 1992
Haynes, Raymond, Haynes, Roslynn, Malin, David, McGee, Richard, Explorers of the Southern Sky, Cambridge University Press, 1996
Russell, H., C., "Report of Astronomer for 1874 & 1875', New South Wales Government Printer, 1876
Geoff Barker, August, 2007