... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... The Troughton equatorial, 2-inch aperture, 3-feet focal length, arrived in December 1795 and was mounted, in the English style, under the south dome on two stone piers resting on a massive pillar, round which the staircase of the dwelling house winds. There is no polar axis, but the right ascension circle, 4 feet in diameter, is attached to the polar pivots by four stays. ... Other virtual visits . ...