Leaving this it expands into the Lake of Horns, having been dammed back in antiquity.
Within the city limits, is dammed a short distance south of the city, and 16,000 horse-power is generated, part of which is transmitted to the city.
The harbour, sheltered by a breakwater, will admit vessels of 300 tons at high water; and the river has been dammed to form a basin for the canal which runs to Launceston.
By this time the rainy season has thoroughly set in, and the field is dammed up so as to retain the water.
The city proper lies on both sides of the little river Alster, which, dammed up a short distance from its mouth, forms a lake, of which the southern portion within the line of the former fortifications bears the name of the Inner Alster (Binnen Alster), and the other and larger portion (2500 yards long and 1300 yards at the widest) that of the Outer Alster (Aussen Alster).