Soon appears Blackrock, a small promontory, on which is a structure suggesting an ancient castle, built on a tongue of land extending into the clear water of the river. The mansion, however, is old only in style and outline, for it is of modern construction. Blackrock is supposed to be the place from which William Penn, the founder of Pennsylvania, set sail, A. D. 1682, landing after a passage of six weeks. We were for the hour sumptuously entertained. Small castles, coves, headlands, near and distant scenery, and a luxurious vegetation lent a fascination and charm, which was but the beginning of a series of similar entertainments, not to end till after the first of September. CORK. Arrived at the castle, not far in the distance is seen, through the opening of the hills making the river banks, the shipping of the city of Cork, which is practically the capital of South Ireland. We find it a large commercial metropolis, built closely on both sides of the River Lee. The latter is parted at the city, and thus the left side of Cork stands mainly on an island, connected with the other side by nine stone or iron bridges. It has in all a population of 97,887, and is the third city of Ireland in importance and commerce, being excelled only by Dublin and Belfast. On one side of the river as we pass into the city, at our left hand, are shipyards, repair and dry docks, and a vast amount of work of the kind is done. It may be added, there is presented to view in the harbor a forest of masts, and here may be seen the shipping of all nations. Near these and just above them, up along farther in the city and bordering the river, are fine Boulevards,--narrow parks or promenades well graded, called the Mardyke, and set out with shade-trees. The opposite side of the river, at the entrance of the harbor proper, is occupied by elegant lawns, with shrubbery and shade-trees in front of fine mansions and villas; and again, along the river above these, begins the business part of the city. A good quay extends half a mile on both sides of the river. These have walls of cut, dark limestone, crowned by a substantial railing as a protecting balustrade. The larger part of the place, so far as its business portion is concerned, is built on level ground, and here the streets are wide, well paved and clean, and with the buildings, all of which are of brick or stone, a majority of the latter being painted in light colors, present a pleasing and finished appearance. All things seen are anything but what is imagined by a stranger when he hears one speak of Irish Cork.