IX. Observations on the currents and undercurrents of the Dardanelles and Bosphorus, made by Commander J. L. Wharton, of H. M. Surveying-Ship 'Shearwater,' between the months of June and October, 1872. From a report of that officer to the hydrographer of the admiralty. Communicated by Admiralty

There is a general flow of the Black-Sea water through the Bosphorus, Marmara, and Dardanelles to the Mediterranean, probably caused by the combination of three things:—first, the prevalence of N. E. winds in the Black Sea; secondly, the excess of water received from the large rivers over the amount lost by temperature at some seasons; and, thirdly, the difference of specific gravities in the two seas. Of these, observation goes to prove that the wind has by far the greatest influence.