The reconstructed Leviathan of Parsonstown. (The original was the largest telescope in the world from the time of its construction by the Third Earl of Rosse in 1843 until the early years of the 20th century.)  The mirror cell holds a surprise for those of us steeped in such arcania: the mirror is supported by a whiffle-tree structure -- just as are the segments of today's world's largest telescopes, the multi-mirror ten-meter instruments of the Keck Observatory on Mauna Kea. I know of no other instruments in which that strategy is utilized.