At 1 A.M. on the morning of the 24th we were again under steam, and soon after daylight speed was slackened as we lay off Mazagan. The abruptness of the transition from deep blue water in the offing to a somewhat milky green where the ship gets into shallower water here attracted our notice. It is of common occurrence even on coasts where there is reason to believe that the bed of the sea shelves vary gradually away from the shore, and one might expect a gradual change of tint; but no satisfactory explanation occurred to us.[2] It was some time before the land came in sight, and we were able to make out the square tower of the Portuguese fort that marks the position of Mazagan. The town stands on a slightly projecting point of land facing northward, and therefore especially exposed to the north-east breeze that prevails throughout the spring and summer. We lay all day rolling heavily, and the surf, breaking in hills of foam upon the shore, was too high to allow of the landing of cargo; but in the afternoon a small boat put off with provisions. Amongst these was a large freshwater fish, a species of shad, that had been caught in the Oued Oum-er-bia which runs into the sea some five miles east of Mazagan close to the site of Azemour, a ruined town once of some importance. The freshwater fish of the streams from the Atlas may probably offer many objects of interest to the ichthyologist, but do not seem likely to add much to the resources of the cook. We were told that the fine-looking animal which was displayed at table is considered a delicacy; but we found the flesh insipid and cottony, and during our subsequent journey we failed to find any fish worth eating. Neither on this occasion nor on our return did we see any trace of the ruins of Azemour or of the great river Oum-er-bia. This is apparently the chief stream of Marocco. It drains the northern declivity of the chain of the Great Atlas for a distance of 150 miles, and nearly the entire of the extensive mountainous region, a still unknown network of high ridges and deep valleys, that covers nearly half the space between the main chain and the Atlantic seaboard. Like all the other rivers of this country the volume of water varies to an extent unknown in Europe. In dry seasons, when a large part of the waters that descend from the mountains is diverted into irrigation channels, and never reaches the sea, the main stream runs over a shallow bed fordable in many places; but after heavy rains the swollen waters have such a rapid current that we were told of travellers being detained a week or ten days waiting for the opportunity of crossing it. Lieut., afterwards Admiral, Washington[3] estimated the breadth of the river where he crossed it, near Azemour, at 150 yards, and found it much the same at about eighty miles from the sea on the return journey from Marocco to the coast.