Herstmonceux Science Centre

Herstmonceux Science Centre

The Equatorial Group of Telescopes forms the former Royal Greenwich Observatory's equatorial telescopes and workshops, now an education centre. Built between 1953 and 1958, it was designed by Brian O'Rorke for the Admiralty, with Derrick Oxley of the Civil Engineer's Department, Admiralty, serving as engineer.

The buildings are steel-framed and clad in traditional Sussex red bricks with grey brick headers. Portland stone forms the window surrounds and dressings. All structures employ cavity wall construction with insulation to prevent heat build-up that would distort observations at night. The workshops feature a copper roof to the rear of the flat roof. Light steel domes are of insulated cavity wall construction clad in copper. The telescopes are independently mounted on deep foundations separate from the building structure itself.

The site is organised on a reinforced concrete bastion clad in brick, with areas of squared knapped flint and York stone paving. The plan comprises six domes of various sizes arranged symmetrically in two rows of three. The northern row houses reflective instruments and is linked by workshops for mirror resilvering or aluminizing and standardisation laboratories. Access is gained from the west side via broad entrance gates, a bridge, and two flights of steps with pebbled surrounds. This leads to the side of a central pool connecting the central dome of each row—the largest of the northern row with the smallest dome overall. The bastion is laid out as a garden with York stone paths, pebbled areas, stone kerbs, and raised walkways on brick and flint walls with stone steps. The two outermost domes in the southern row are the largest of all and are set proud of the bastion, connected to it via short bridges. The bastion provides secure entrance to the site while giving the group the character of an early eighteenth-century landscape feature overlooking the park.

The northern group originally had an entrance under the central dome, now blocked but retaining steps incorporating spheres, a repeated architectural motif. Steel-framed tripartite windows between Portland stone surrounds have louvred blinds to control heat. At each end, doors with carefully designed bronze handles are positioned so that when closed the handles point downwards within the frame of the mullion. These doors are set on steps within the framed surround, supported on smaller spheres. Rooftop balconies have steel balustrades with paired balusters set in surrounds supported on tiny domes. Similar balustrade forms line balconies to the domes. On the south side, the smallest central dome incorporates a gazebo at the end of the pool. Many buildings display a date set on the hopper head of lead downpipes, with 1955 set between anchors being the most frequent.

Workshop blocks are linked under the central dome, with corridors in double-height spaces to either side facing south. The upper landing features a balcony whose thin balusters are supported on steel spheres. Hornton stone forms the flooring, door surrounds, and central piers. The upper corridors retain their original timber-panelled doors and have woodblock floors. All the domes are similarly constructed, with floor levels of varying heights reached by stairs and with timber-panelled walls. All domes revolve and have opening shutters to permit observations. The south-western dome housing the 26-inch Thompson refractor is mounted independently of the floor, which rises and falls for the convenience of astronomers making observations at different points of the sky. The Science Centre retains the 26-inch refractor of 1896 and the 36-inch reflector of 1932, along with other telescopes brought by the Royal Greenwich Observatory to Herstmonceux. The main axes of the telescopes are tilted to lie parallel to the Earth's rotation axis, known as an "Equatorial" mounting—more complex to construct than other mountings but easier to use, lending the group its name.

Brian O'Rorke's drawings for the scheme date from 1951 to 1952. They reveal that while the Admiralty pre-determined the components of the design, their disposition and their raising on a bastion were devised by O'Rorke. He wrote on the drawings that inspiration for the layout came while in the bath. The shutters to the domes are also an innovation of O'Rorke's and were considerably lighter than those in use elsewhere.

The Royal Observatory moved to Herstmonceux to escape the atmospheric pollution and glare that made observations at Greenwich impossible. In 1984 it relocated again, to the Roque de los Muchachos Observatory at La Palma in the Canary Islands. The Equatorial Group represents the most distinguished of the Royal Greenwich Observatory's buildings at Herstmonceux—a conscious expression of modern science in traditional local materials, adopting the guise of eighteenth-century garden temples without deflecting from scientific purpose. The quality of materials and detailed finishes are exceptional, and the Equatorial Group ranks among the most important government commissions of its period. It is also the leading work of its architect, Brian O'Rorke (1901–74), who made his name as an interior designer for the Orient line of ships, flying boats, the Coronation Scot, and early aircraft. He was also a distinguished architect whose scheme for the National Theatre was never constructed, and whose few surviving works merit greater recognition.

The grounds of Herstmonceux Castle, itself listed Grade I, are on the Register of Historic Parks and Gardens, to which the Equatorial Group makes an important contribution.