Admiral de Mello had been true to his word, and had obeyed the order which had reached him through the proper channel. He was within a hundred miles of Port Said when the despatch-boat, with the Agent of the Republic, had been met. He at once changed his course, and steamed towards the city he had so lately left. His fleet consisted of two battleships, which, though slow and out of date, were yet formidable machines, two cruisers, and a gunboat. The inopportune bursting of a steam-pipe on board the flagship, the Fortuna, caused a delay of several hours, an............