Cleaning the drive and speed regulator

An astronomer will often observe a particular star over a considerable length of time. Because Earth is slowly rotating in relation to the stars, the star will move out of view if the telescope is fixed. To compensate for this, telescopes are fitted with a drive mechanism that moves them in the opposite direction but at equal speed to Earth’s rotation.

Macdonnell’s telescope is driven by a falling weight inside the telescope pedestal, with a centrifugal regulator controlling the rate of movement. When the Museum acquired the telescope, the regulator unit was clogged with old oil and grease. It was cleaned and some of the gear meshes were re-adjusted. But one gear wheel, which does not connect to anything, continues to baffle the conservation team.