Papers regarding the operation to discover the longitude of Edinburgh by means of electric telegraph. The papers include material on the arrangement of stars for observation; calculations of longitude at Edinburgh deduced from observations; and instructions and arrangements for those involved in the tests, including J. Washington, W. Ellis, C.V. Walker, C.P. Smyth, J.C. Clark and C.F. Varley. There are also letters on the longitude of Paris by U.J.J. Le Verrier, of Brussels by L.A. Quetelet, and of Vienna by J.V. Littrow; and on the differences in longitude between Konigsberg and Pillau (Baltiysk), Berlin and Konigsberg, Fredericton and Cambridge (U.S.A.), Chicago and Quebec, Cambridge (U.S.A.) and Quebec, and Berlin and Brussels. The methods employed in the work are explained in an 'account of experiments for testing various methods for determining longitude by electric telegraph'.