Leaving this it expands into the Lake of Horns, having been dammed back in antiquity.
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.
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 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).
Deep valleys winding through the barren foothills lead gradually up to the higher mountains, and as the track ascends the scenery and vegetation change their character; the trees which line the banks of the wadi are overgrown with creepers, and the running stream is dammed at frequent intervals, and led off in artificial channels to irrigate the fields on either side; the steeper parts of the road are paved with large stones, substantially built villages, with their masonry towers or da y s, crowning every height, replace the collection of *mud walls and brushwood huts of the low country; while tier above tier, terraced fields cover the hill slopes and attest the industry of the inhabitants and the fertility of their mountains.