The harbour is artificial.  A broad straight pier, three hundred yards in length, and upon which the storehouses were built, projects from a point about a quarter of a mile from the north extremity of the town.  A mole is carried from the end of this pier, which bends in a south-westerly direction towards the town, forming nearly a quarter of a circle.  Opposite the mole-head is a small insulated pier, which leaves the entrance to the harbour about a hundred and twenty yards wide.  The rock upon which the mole is built extends about two hundred yards to the N.E. beyond the angle at which the pier joins it.  The shores recede considerably from the base of the pier, forming a small bay on either side of it.

All the works around the harbour were covered with the strongest fortifications.  Immediately beyond the pier-head stood the Lighthouse battery, a large circular fort, mounting between sixty and seventy guns, in three tiers.  At the extremity of the point of rock beyond the lighthouse was a very heavy battery, of two tiers, mounting thirty guns and seven mortars in the upper.  The mole itself was filled with cannon, like the side of a line-of-battle ship, mostly disposed in a double tier, with ports below, and embrasures above; but the eastern batteries, next the light-house, had an inner fortification, with a third tier of guns, making sixty-six in these batteries alone.  All these batteries had together above two hundred and twenty guns—­eighteen, twenty-four, and thirty-two pounders; besides two, at least sixty-eight pounders, and upwards of twenty feet long.  On the sea wall of the town were nine batteries; two at the southern extremity; then the Fish-market battery in three tiers, bearing three hundred yards west of the molehead; three between the Fish-market and the gate leading to the mole; one over this gate; and two on the wall beyond it.  Along the shore, within twelve hundred yards south of the town, were three batteries, and a very heavy fort.  Another large fort, and six batteries, commanded the bay to the N.W.  Many guns in other parts of the fortifications of the town, and in forts and batteries on the hills around it, were in situations which enabled them to fire upon ships.  Altogether, the approaches by sea were defended by scarcely less than five hundred guns.

The Admiralty were greatly surprised when Lord Exmouth proposed to attack these works with five sail of the line.  Many naval officers who were consulted by the Board considered them unassailable.  Nelson, in a conversation with Captain Brisbane, had named twenty-five line-of-battle ships as the force which would be required to attack them.  The opinion was not founded upon his own observation, and he was evidently misled by the errors in the received plans; for that number of ships could not have been placed before the town; but it marks his sense of the great danger in attacking powerful batteries with ships, and of the tremendous strength of Algiers.  Lord