The sides of the wide valley in which the Meuse runs are sharply cut, and are clothed for the most part with scrub, oak, and beeches. Here we find the Black Country of Belgium, the chief coal-mining district of the country, where the smoke from many factory and colliery chimney-stacks darkens the sky. The chief centre of this Black Country is Liége, which stands in a strikingly picturesque situation on the lofty banks of the broad Meuse not far from its junction with the Ourthe. Most of the city stands on the left bank of the river, and here we find noble public buildings, stately churches, pretty parks, broad boulevards, and spacious streets. On the right bank is the industrial quarter, with many factories and the homes of the workers. There is an island in the river, by means of which several bridges unite the two portions of the city. Firearms are largely manufactured by the people in their own homes; and zinc foundries, engine shops, motor-cycle works, a gun factory, a cannon foundry, and flax-spinning mills give employment to thousands of other workmen. The inhabitants are Walloons, who have always been renowned for their independence and love of freedom. Brialmont fortified Liége by building around it a series of twelve forts in a ring some ten miles across. From the little plan on page 236 you will see that these forts were at distances varying from 6,500 yards to 10,000 yards from the centre of the city. In the old days forts were strong castles, usually built on a high rock or hill; but when guns of great range and force came into use, engineers sank their forts into the earth as much as possible. To outward appearance a Liége fort seemed to be nothing but a low, grassy mound rising from a deep ditch. The mound was cased in with concrete and masonry, and its top was broken by a pit in which was fitted a "cupola," or gun-turret, which could be made to slide up and down by means of a piston. When the cupola was down, nothing was visible but the low mound; when it was up, the muzzles of the guns were seen sticking out of portholes. Inside this great molehill were the quarters for the garrison, the machinery for moving the guns and cupolas, the ammunition and supply stores, the electric-lighting arrangements, and the ventilating fans. The engineers and gunners entered and left the fort by means of a tunnel. You will see a diagram showing the structure of one of the most powerful of the Liége forts on page 229.