Correspondence on the installation of the Duke of Northumberland's telescope at the University Observatory, Cambridge. The letters covers the initial purchase of the telescope, the refinements made to it, the construction of a new dome to house it, its mounting and its installation. The correspondents include the Duke of Northumberland, Sir F. Beaufort, J. Challis, E.J. Cooper, J. Glaisher, J.F.W. Herschel and many builders and instrument makers. There are various sketches and plans, as well as receipts and inventories for the completed work.