I was early awake this morning, in order to finish exploring Cologne before six, the starting hour for Aix. Escorted by a young cicerone, who 'politely volunteered his services,' I went first to the cathedral, one of the most celebrated on the continent. Five hundred years have elapsed since this edifice was commenced, and yet it is scarcely half finished! The choir only is quite completed, and this is very elaborately decorated within and without. The grass is actually growing on the towers, which have as yet attained but one third of their intended elevation, (five hundred feet,) and being connected with the choir merely by a temporary structure, they look like ruins of a separate edifice. Yet, even in its present state, the cathedral of Cologne is a wonderful specimen of human ingenuity and perseverance. I followed my cicerone to the head of the choir, behind the great altar, where he pointed to a richly-ornamented monument, as the tomb of the 'Three Kings of Cologne.' It is to be hoped you are versed in the veritable history of these same three kings, as well as that of the eleven thousand virgins before-mentioned, for neither memory nor time will permit me to edify you in 'legendary lore.' Mass had already commenced, at this early hour, and the good people were kneeling reverently on the marble floor, saying their paternosters and counting their beads, or watching, with humble simplicity, the movements of the priest before the altar. I observed one of the boys employed to swing the censers of burning incense, turn round occasionally, with a piteous yawn. The painted windows in this cathedral are very elaborate and beautiful. I had time to 'drop in' to several other churches during matins, where I saw much that was curious and dazzling, and heard some fine organ-music. There were twenty-two passengers 'booked' for Aix, and according to law, they were obliged to send extras for as many as applied before the hour. This route to Brussels and Ostend is much travelled by the English, in preference to continuing on the Rhine to Rotterdam. It was a bright morning again, and the ride proved rather pleasant, though somewhat monotonous. The country, for several miles out of Cologne, is nearly level, and almost quite treeless: near the city, it is laid out in one vast vegetable-garden, without any enclosure, as is often the case on the continent. Poaching does not seem to be dreamed of. The fortifications of Cologne, and those of Juliers, our first stopping-place, are of the most substantial kind. Juliers is surrounded by three distinct walls, each about twenty feet thick, and separated by broad deep ditches, or canals. And yet in the present _refined_ state of the art of war, this fortress is far from being impregnable.