Reflecting telescope, Paris Observatory, 1884.
© Science Museum / Science & Society Picture Library
Photograph of one the telescopes at the Paris Observatory in France taken around 1884. This view shows the shows an equatorially mounted reflecting telescope of 120 cm (47 inch) aperture completed in 1877. Constructed by A Martins, Eichens and Paul Gautier, the telescope used a silver-on-glass mirror. Protected by a moveable building, the telescope was used in the open-air with viewing platform that moved on a circular set of rails. The telescope was of limited use as the slightest breeze caused the instrument to tremble, a fault that ruined the view.