Caption: The 1.83-meter (72-inch) Leviathan of Parsonstown was the record largest telescope (i.e., the telescope with the largest primary) until 1917 when it was superpassed by the 2.54-meter (100-inch) Hooker telescope at Mount Wilson Observatory in California (see Wikipedia: Timeline of telescopes, observatories, and observing technology: 1800s). The Leviathan was operational 1845--c.1890 (see Wikipedia: Leviathan of Parsonstown: Operation).