Hurrying on its way with the leaps and falls that are characteristic of mountain streams, our river is first joined by the Henwen brook, a tiny stream that has the honour of forming a part of the boundary-line between two shires. Beyond the wooded vale of Cwm Wysc the Usk receives the Hydfer, and at length comes to Trecastle, once a place of rare show and importance, but now modest enough in all conscience. Here may still be seen a mound and large earthworks of Bernard Newmarch's Castle. Below this village the Usk receives the waters of Drayton's "Cray," the first stream of real importance that flows into the greater river; and, after leaping a ledge of rock in a beautiful fall, continues its way through a tract of country once the hiding-place of a swarm of determined robbers and outlaws--the Forest of Brecon. At one time this region lay at the mercy of these desperadoes; and it seems to have been necessary for Edward III. to build castles for the protection of people compelled to journey through the forest. Henry IV. sojourned in one of these fortresses in 1403, and thence issued a general pardon to all the rebels who would cease from troubling; but the chances are that this wild and well-nigh inaccessible district offered more attractions to the turbulent robbers than did the prospect of hard and honest work, coupled with the king's pardon. The Usk now receives a goodly contribution from the Yscir; and between the two streams are the remains of a Roman camp, the Gaer, rectangular in form and believed to have been in command of Ostorius Scapula. The ruins of this fort are remarkably well preserved, the walls in places standing six feet high, although partly overgrown with bush. Many valuable coins and other curiosities belonging to the Roman period have here been excavated. Inclining to the south, the Usk now flows through a lovely bit of wooded country, and reaches the village of Llanspyddid, where an attractive view is to be had of the river, still in its youth, running with merry song over shallows and between high picturesque banks. Brecon, occupying a highly picturesque situation, is the first place of any importance that the Usk comes to in its flight from the mountains. Two streams join the river at this point, the Tarel and the Honddu; and, as the town is ringed completely round with high mountains, it may be said to lie in the bottom of a huge bowl. Near by, the Beacons, twin peaks, the highest mountains in South Wales, tower to the sky, and add grandeur to the beauty of the neighbouring hills. In the reign of good Queen Bess, Churchyard was moved to verse at the sight of Brecon and its surroundings. Thus he sings:--