The McClean 10/12-inch twin tube refracting telescope (1896)

Made by Sir Howard Grubb in Dublin in 1894, The McClean telescope is a twin tube refractor of 10-inch main viewing tube and 12-inch photographic tube. The telescope is of similar pattern to some 50 instruments made for the International Astrographic Survey of 1896. Similar instruments can be found in many observatories dating from the beginning of the twentieth century. Variations mainly occur in the size of the photographic tubes.

Originally this telescope was one of a pair of such telescopes erected in the garden of Frank McClean near Tonbridge Wells. McClean's son gave the telescope to Lockyer in 1912 to help found the Norman Lockyer Observatory at Sidmouth, the other going to the Radcliffe Pretoria Observatory in South Africa.

The McClean telescope was given a major refit in 1989 and the dome in 1997. The original clock-work control was replaced by an electric drive and new objective lenses fitted to the photographic tube. In 1993 the telescope's electric drive was further modified for greater accuracy by an electronic control. The telescope has an equatorial German mounting.

At the Norman Lockyer Observatory The McClean telescope is the principal instrument for the programme of scientific observations and may not be available for public viewing when the observatory receives visitors at night. The instrument has been adapted for work with a CCD camera and computer enhanced imaging.

The telescope is ideal for use within the solar system, and was perhaps the first European instrument to see holes in Jupiter's clouds when Comet Shoemaker Levy struck in 1994. The main use for the telescope now is in the study of deeper space objects such as nebulae. The photograph shows how sunspots are shown by eyepiece projection, but this demonstration is now made on the Lockyer telescope.