Yale Parallax Refractor

66 cm (26 inch)



Summary; History; Current; Technical; Sources; Links; Gallery:


In brief

Important  Contributions:
Groundbreaking work was done with this telling measuring the parallax and proper motions of stars in the Southern Hemisphere.


  • This instrument was specially designed and built for the determination  of trigonometrical parallaxes.
  • The  instrument used a 26-inch refractor that was a specialist telescope designed for the task. To measure a star’s parallax,  it is essential for the star to be high in the sky when the relevant photographs are taken – so there was no need for the telescope  to be wholly maneuverable, or to cover the whole sky. As long as it could be pointed some way to either side of the meridian,  it would serve its purpose very adequately.
  • The  program to measure parallax in the Southern Hemisphere came to an end in 1952. Due to growing light problems in Johannesburg,  it was decided to move the telescope to Mount Stromlo in Australia.
  • On 18 January 2003 a bush fire destroyed Mount Stromlo Observatory with all its instruments. The 26-inch refractor was also destroyed. (A section of the lost and found page is dedicated to this tragedy)

Historical Background

Yale University.

Where  Located:


Concerning the maneuverability of the telescope, there was one great telescope which was even more restricted and whose tube was swung between two massive stone  walls so that it could point only a short way to either side of the meridian. This was the 72-inch reflector built at Birr Castle in Ireland, by the third Earl of Rosse in 1845 – and with which  he discovered the spiral forms of the systems we now know to be  external galaxies. However, Lord Rosse followed this pattern not  because he wanted to, but because with the limited engineering facilities available at the time he had no choice. The 72-inch was last used  in 1909, and is still to be seen in the Castle grounds. Up to until  the middle of the First World War, it remained the largest reflector  in the world, though it had a metal mirror and was by no means the  equal of some of the smaller but newer instruments. [Copied from  Moore, p.112]

Current  Information

Present  Location:
Mount Stromlo Observatory in Australia


On 18 January 2003 a bush fire destroyed Mount Stromlo Observatory with all its instruments. The 26-inch refractor was also destroyed.

Damaged beyond repair.

Technical Details

Type: Photographic Refractor
Aperture: 26 inch (66 cm)
Focal Length: “Long focal length” [Moore, p.112.]
Operational History:

  • Johannesburg:  As the telescope could not rotate, they build “an observatory of a very unusual kind. There was no majestic dome, or even a  turret; the observatory took the form of an asymmetrical brick  structure, with a slit in the roof which could be opened but which  did not rotate”. [Copied from Moore, p.111.]
    Picture of building in Moore, P. & Collins, P., Astronomy  in Southern Africa, p.112.


Link to the Main Bibliography Section and more information about Sources.


Pictorial  Sources:


  • Moore, P. & Collins, P., Astronomy in Southern Africa, p111 – 113.  (General Source)
  • Stoy,  R.H., Astronomy in South Africa, A History of Scientific Endeavour  in South Africa, Royal Society of South Africa, 1977.
  • Smits  P. A Brief History of Astronomy in Southern Africa. (Unpublished).




The 26 inch Yale telescope after it’s move to Mount Stromlo Observatory in Australia.
Source: Personal communication with Wayne Orchison

The 26 inch Yale after the fire at Mount Stromlo Observatory in Australia. On 18 January 2003 a bush fire destroyed approx. 500 houses and the Observatroy. Five other telescopes were destroyed with the 26 inch.
Source: Personal communication with Wayne Orchison