The largest telescope in Europe

The Isaac Newton astronomical telescope at the Royal Greenwich Observatory, Herstmonceaux Castle, Sussex, is the largest in Europe. The main mirror is 98 in (2.5 m) in diameter and 16 in (41 cm) thick. Designed by Grubb Parsons, the telescope – weighing 100 tons – is housed within a dome which is accurately balanced and levelled on a track 56 ft above ground level.

The building housing the telescope is of steel-framed construction, circular in plan of 60 ft diameter and 60 ft high. Steelwork comprises sixteen 18 in by 7½ in by 66lb universal beam stanchions 55 ft high. Steelwork is grit blasted, zinc sprayed and painted with one coat of calcium plumbate.

Floor beams are at 36 ft 6 in and 48 ft levels with a cantilever balcony at 48 ft. This balcony is for the use of observers. The main staircase is of all-welded mild steel construction. The building is clad with aluminium sheet. Heavy steel reinforcing rods contributed to the great strength needed in the concrete foundation to support the weight of the telescope and its ancillary equipment.

Superintending civil engineer: D H Little, OBE BSc MICE Ministry of Public Building and Works.