Portable transit telescope

Telescope and stand for portable transit telescope. From a transit of Venus expedition of 1874, used at Station A (Egypt).

Transit instruments 'B' sent to Honolulu, 'C' [AST0986] sent to Rodriguez Island and 'D' [ZBA1731] sent to Christchurch, New Zealand, were later used for time-determination at the Royal Observatory, Greenwich and then at its outpost at Abinger between 1927-1957. In 1967 'C' was presented to the NMM while 'D' remained with the Royal Greenwich astronomers until the closure of the RGO in 1998 when it returned to the original Greenwich site. This telescope, transit instrument 'A', which had been sent to Egypt and then to the Royal Observatory at the Cape returned to Greenwich in 1977.

This telescope was altered sometime after the transit of venus expedition, alterations include an electric attachment for getting uniform illumination across the cross-wires on the eyepiece.

Telescope: 3 inch aperture telescope with a 36.5 inch focal length.

Stand: The original stands for each of the 5 transit of Venus transit instruments had been stone piers, 4ft 11 inches high, each weighing 1400lb. This transit instrument now sits on a display mount made for it by the Museum.

Box and accessories: would originally have fitted into two travelling cases. These are now missing.

Object Details

ID: AST0963
Collection: Astronomical and navigational instruments
Type: Telescope
Display location: Not on display
Creator: Troughton & Simms
Places: Christchurch; Venus
Events: Transit of Venus, 1874
Date made: 1866; 1870
People: Airy, George Biddell
Credit: National Maritime Museum, Greenwich, London
Measurements: Overall: 533 x 457 mm
Parts: Portable transit telescope