Merz telescope at the Royal Observatory, Greenwich, London, England. This is the 12.75-inch Merz telescope, which was used for planetary observations. The mount (lower left) is an equatorial mount, helping astronomers to accurately track stars and planets across the sky. This telescope, made by Merz of Germany, was mounted on this base in 1859. This telescope was replaced in 1893 by a larger telescope, the famous 28-inch refractor. Artwork published in the 1891 edition of The Midnight Sky, by the British astronomer Edwin Dunkin.