With respect to the great East African ocean-current, which has given rise to so many fables gravely recorded by the Arab geographers,[36] the best authorities at Zanzibar are convinced, and their log-books prove, that both its set and drift, like the Brazilian coast-stream, are in the present state of our knowledge subject to the extremes of variation. The charts and Horsburgh lay it down as a regular S.W. current; and so it is in the southern, whilst in the northern part it is hardly perceptible. Between Capes Guardafui and Delgado it flows now up then down the coast; here it trends inland, there it sets out to sea. Dr Ruschenberger relates that on Sept. 1, 1835, his ship, when south of Zanzibar, was carried 50 miles in 15 hours, and was obliged to double the northern cape. The same happened to Captain Guillain in August 1846, when he lost five days. This resulted from the superior force of the S.W. monsoon, which often drives vessels to the north 30 to 40 miles during the day and night. Lieut. Christopher (Journal, Jan. 5, 1843) reported it to be variable and violent, especially close in shore, and observed that it frequently trends against the wind. It is usually made to run to the S.W. between December and April, at the rate of 1·3 miles per hour, from Ra’as Hafun to Ra’as Aswad, and two to three miles per hour between Capes Aswad and Delgado. Shipmasters at Zanzibar have assured me that when this coastal current covers three knots an hour there is a strong backwater or counter-flow, which, like the Gulf-stream, trends to the north, and against which, with light winds, native vessels cannot make way. This counter-current has extensive limits; usually it is considered strongest between Mafiyah and Pomba. The ship St Abbs, concerning which so much has been said and written of late years, was wrecked in 1855 off St Juan de Nova of the Comoro group (S. lat. 17° 3′ 5″), and pieces of it were swept up to Brava (N. lat. 1° 6′ 8″), upwards of 1000 miles. The crew is supposed still to be in captivity amongst the Abghal tribe; and in 1865 an Arab merchant brought to Zanzibar a hide marked with letters which resembled N F B N. A writer in the _Pall Mall_ opined the letters to be ‘Wasm’ or tribal brands, justly observing that ‘all the Bedawin have these distinguishing marks,’ but forgetting that he was speaking of the analphabetic Somal, to whom such knowledge does not extend. As we might expect, the Mozambique stream, south of Cape Delgado, always flows southerly with more or less westing. The rate is said to vary from 20 to 80 miles a day.