18 cm (7 inch)
This instrument was sent to the Cape Observatory due to the influence of John Herschel. In 1838 in a letter to the Admiralty Herschel indicated that he was anxious that the double stars that he discovered in 1834 – 38 should be re-observed with an instrument of adequate power. Several attempts were made to find an English instrument of high quality. Herschel exhaustively tested a Simms 8-inch lens, which he eventually rejected. He eventually settled on this 7-inch refractor built by Merz of Munchen. [Warner – Astronomers, p.63.]
Cape Observatory. Used as finder scope on the Cox – Hargreaves telescope.
S.A.A.O. (At head office in Cape Town)
Type: Reflector / Refractor
Focal Length: 7 inch (17.78 cm)
Mirror / Lens:
Attachments: Browning Spectroscope
Manufacturer: Merz of Munchen.
Building: In approximately 1849 a new dome was built at the Cape Observatory, 14 ft (4.2 meters) in diameter, in an almost symmetrical setting, 53 yards (48.5 meters) to the north of the East Wing. The framework for the dome was sent out from England, and overlooked when the vessel docked at the Cape. It was found and retrieved from Madras in India seven months later. The dome rotated on six cannon balls. [Warner – Astronomers, p.63.]
Note: Warner stated that the dome rotated on three cannon balls, where in fact it is on six balls.
Note: Koorts refer to this instrument as Mertz, and Warner as Merz.
- Koorts, W.: The 1882 transit of Venus: The British expeditions to South Africa; MNASSA April 2004, Vol. 63 nos. 3 & 4, pp. 34 – 57.
- Warner, B., Astronomers at the Royal Observatory Cape of Good Hope.