4 inch (10 cm)
Used since 1910 to take two photographs of the sun per day (weather permitting). The photos were sent to Royal Greenwich Observatory.
Used occasionally for public viewing.
Type: Reflector / Refractor
Aperture: 4 inch (10.16 cm) giving an 8-inch (20.32-cm) picture
Mirror / Lens:
Building: The heliometer stood in the dome which first housed the 7-inch Mertz telescope. A unique feature of the dome is that it revolves on six cannon balls. [Koorts p. 52]
- Koorts, W.: The 1882 transit of Venus: The British expeditions to South Africa; MNASSA April 2004, Vol. 63 nos. 3 & 4, pp. 34 – 57.
- Laing, J.D. (ed.), The Royal Observatory at the Cape of Good Hope 1820 – 1970 Sesquicentennial Offerings, p.32.
The Heliometer Observatory. Sketches are part of a compilation of sketches concerning the Cape Observatory.
Left hand sketch published by “The Graphic”, 27 August 1892. Courtesy of Africana Museum, Johannesburg. Source: Moore
Right hand sketch published by “The Cape Times”, 19 September 1908. Source:Warner, Astronomers