Paris, Saturday, July 19, 1851.

From Cologne westward by Railroad to the Western frontier (near Verviers) of Rhenish Prussia, and thus of Germany, is 65 miles. For most of the way the country is flat and fertile, and in good part devoted to Grazing, though considerable Wheat is grown. The farming is not remarkably good, and the general aspect befits a region which for two thousand years has been too often the arena of fierce and bloody conflict between the armies of great nations. Cologne itself, though a place of no natural strength, has been fortified to an extent and at an evident cost beyond all American conception. All over this part of Europe, and to a less degree throughout Italy, the amount of expenditure on walls and forts, bastions, ditches, batteries, &c. is incalculably great. I cannot doubt that any nation, by wisely expending half so much in systematic efforts to educate, employ steadily and reward amply its poorer classes, would have been strengthened and ensured against invasion far more than it could be by walls like precipices and a belt of fortresses as impregnable as Gibraltar. But this wisdom is slowly learned by rulers, and is not yet very widely appreciated. Whenever it shall be, "Othello's occupation" will be gone, not for Othello only, but for all who would live by the sword.

For some miles before it reaches the frontier, and for a much larger distance after entering Belgium, the Railroad passes through a decidedly broken, hilly, up-and-down country, most unlike the popular conception of Flanders or Belgium. Precipices of naked rock are not unfrequent and the region is wisely given up mainly to Wood and Grass, the former engrossing most of the hill-sides and the latter flourishing in the valleys. This Railroad has more tunnels in the course of fifty miles than I ever before met with—I think not less than a dozen—while the grading and bridging must have been very expensive. Such a country is of course prolific in running streams, on which many small and some larger manufacturing towns and villages are located. At length, it ascends a considerable inclined plane at Liege, once a very popular, powerful and still a handsome and important manufacturing town with 60,000 inhabitants; and here the beautiful and magnificently fertile table lands of Belgium spread out like a vast prairie before the traveler. In fact, the peasant cultivators are so commonly located in villages, leaving long stretches of the rarely fenced though well cultivated plain without a habitation, that the resemblance to level prairies which have been planted and sown is more striking than would be imagined. But the growing crops are too cleanly and carefully weeded and too uniformly good to protract the illusion. Sometimes hundreds of acres are unbrokenly covered with Wheat, which has the largest area of any one staple; but more commonly a breadth of this is succeeded by one of Rye, that by one of Potatoes, then Wheat again, then Clover, then Rye, then Wheat, then Potatoes, then Clover or other grass, and so on. I never before saw so extensive and uniformly thrifty a growth of Potatoes, while acres upon acres of Beets, also in regular rows and kept carefully free from weeds, present at this season a beautiful appearance. I apprehend that not half so much attention has been given in our country to the growth of this and the kindred roots as would have been richly rewarded. Of course, it is idle to sow Beets on any but rich land, with a generous depth of soil and the most thorough cultivation, but with such cultivation the red lands of New-Jersey and the intervales of our rivers might be profitably and extensively devoted to the Beet culture and to that of the larger Turnips. I have seen nothing in Europe that made a better appearance or promised a more bountiful return than the large tracts of Belgium and the neighboring district of France sown to Beets.

Indian Corn and the Vine are scarcely, or not at all seen in Belgium. Beggars are not abundant; but women are required to labor quite extensively in the fields. The habitations of the poor are less wretched than those of Italy, but not equal to those of the fertile portion of Switzerland. Irrigation is quite extensively practised, but is far from universal. The few cattle kept in the wholly arable and thoroughly cultivated portion of the country are seldom allowed to range, because of the lack of fences, but are kept up and fed throughout the year. Women cutting grass in all by-places, and carrying it home by back-loads to feed their stock, is a common spectacle throughout central Europe. Trees sometimes line the roads and streams, or irrigating canals, and sometimes have a piece of ground allotted them whereon to grow at random, but are rather scarce throughout this region, and I think I saw square miles entirely devoid of them. Fruit-trees are clearly too scarce, though Cherries in abundance were offered for sale as we passed. On the whole, Belgium is not only a fertile but a prosperous country.

At Liege, the Railroad we traversed leaves its westerly for a north-west course, running past Tirlemont to Malines (Mechlin) and thence to Antwerp; but we took a sharp turn to the south-west of Malines in order to reach Brussels, which, though the capital and the largest city of Belgium, is barely a point or stopping-place on a right line, while Liege, Namur, Ghent and Bruges are each the point of junction of two or more completed roads. Brussels has slept while this network has been woven over the country, and will awake to discover herself shorn of her trade and sinking into insignificance if she does not immediately bestir herself. Her location is a fine one, on a ground which rises very gradually from the great plain to a modest hill southward, and she is among the best built of modern cities. But already she is off the direct line from either London or Paris to Germany; I would have saved many miles by avoiding her and taking the road due west from Liege to Namur, Charleroi and Mons, where it intersects the Brussels line; and soon the great bulk of the travel will do so if it does not already. Railroads are reckless Radicals and are destined by turns to make and to mar the fortunes of many great emporiums.

NORTH-EASTERN FRANCE.

Tournay in the coal region, fifty miles from Brussels, is the last town of Belgium; eight miles further is Valenciennes, one of the strong frontier fortresses of France, with over 20,000 inhabitants, an active trade and the worth of a dukedom wasted on its fortifications. Here our baggage underwent a new custom-house scrutiny, which was expeditiously and rationally made, and I kept on twenty-three miles farther to Douai, where our Railroad falls into one from Calais, which had already absorbed those from Dunkirk and Ghent, and where, it being after 10 o'clock, I halted for the night, so as to take a Calais morning train at 4½ and see by fair daylight the country thence to Paris, which I had already traversed in the dark.

This country presents no novel features. It is not quite so level nor so perfectly cultivated as central Belgium, but is generally fertile and promises fairly. The Rye harvest is in progress through all this country, and is very good, but the breadth of Wheat is much greater, and it also promises well, though not yet ripened. Westward from Brussels in Belgium is an extensive Grazing region, bountifully irrigated, and covered with large herds of fine cattle. Something of this is seen after crossing into France, but Wheat regains its predominance, while large tracts are devoted to the Beet, probably for the manufacture of Sugar. There are few American gardens that can show the Beet in greater perfection than it exhibits here, in areas of twenty to forty acres. Wood also becomes far more abundant in the Grazing region, and continues so nearly up to the walls of Paris, Poplars and other trees of slender foliage being planted in rows across the fields as well as by the streams and road-sides. The Vine, which had vanished with the bolder scenery of the Rhine, reappears only within sight of Paris, where many of the cultivated fields attest a faultiness or meagerness of cultivation unworthy of the neighborhood of a great metropolis. I presume there will be more middling and half middling yields within twenty miles of Paris than in all Belgium.

I find Paris, and measurably France, in a state of salutary ferment, connected with the debate in the Assembly on the proposed Revision of the Constitution. The best speeches are yet to be made, but already the attention of the People is fixed on the discussion, and it will be followed to the end with daily increased interest. That end, as is well known, will be a defeat of the proposed Revision, and of all schemes looking to the legal and peaceful reËstablishment of Monarchy, or the reËlection of Louis Napoleon. And this discussion, this result, will have immensely strengthened the Republic in the hearts of the French Millions, as well as in the general conviction of its stability. And if, with the Suffrage crippled as it is, and probably must continue to be, a heartily Republican President can be elected here next May, an impulse will be given to the movement throughout Europe which can scarcely be withstood. Live the Republic!