THE RHINE.

After spending the night at Mannheim, I took a steamboat at 5½ this morning for this place, 165 miles down the Rhine, embracing all the navigable part of the river of which the scenery is esteemed attractive. As far down as Mayence or Mentz (55 miles), the low banks and broad intervale continue, and there is little worthy of notice. From Mentz to Coblentz (54 miles), there is some magnificent scenery, though I think its natural beauties do not surpass those of the Hudson from New-York to Newburgh. Certainly there are no five miles equal in rugged grandeur to those beginning just below and ending above West Point. But the Rhine is here somewhat larger than the Hudson; the hills on either side, though seldom absolutely precipitous, are from one to five hundred feet high, and are often crowned with the ruins of ancient castles, which have a very picturesque appearance; while the little villages at their foot and the cultivation (mainly of the Vine) which is laboriously prosecuted up their rocky and almost naked sides, contribute to heighten the general effect. These sterile rocks impart a warmth to the soil and a sweetness to the grape which are otherwise found only under a more southerly sun, and, combined with the cheapness of labor, appear to justify the toilsome process of terracing up the steep hill-sides, and even carrying up earth in baskets to little southward-looking nooks and crevices where it may be retained and planted on. Yet I liked better than the vine-clad heights those less abrupt declivities where a more varied culture is attempted, and where the Vine is intermingled with strips of now ripened Rye, ripening Wheat, blossoming Potatoes, &c., &c., together imparting a variegated richness and beauty to the landscape which are rarely equaled. But the Rhine has been nearly written out, and I will pass it lightly over. Its towers are not very imposing in appearance, though Coblentz makes a fair show. Opposite is Ehrenbreitstein, no longer the ruin described (if I rightly remember) in Childe Harold, but a magnificent fortress, apparently in the best condition, and said to have cost Five Millions of dollars. The "blue Moselle" enters the Rhine from the west just below Coblentz. This city (Cologne) is the largest, I believe, in Rhenish Prussia, and, next to Rotterdam at its mouth, the largest on the Rhine, having a flourishing trade and 90,000 inhabitants. (Coblentz has 26,000, Mayence 36,000, Mannheim 23,000 and Strasburg 60,000.)

There are some bold hights dignified as mountains below Coblentz, but the finest of the scenery is above. The hills disappear some miles above this city, and henceforward to the sea all is flat and tame as a marsh. On the whole, the Rhine has hardly fulfilled my expectations. Had I visited it on my way to the Alps, instead of just from them, it would doubtless have impressed me more profoundly; but I am sure the St. Mary's of Lake Superior is better worth seeing; so I think, is the Delaware section of the Erie Railroad. It is possible the weather may have unfitted me for appreciating this famous river, for a more cloudy, misty, chilly, rainy, execrable, English day I have seldom encountered. To travelers blessed with golden sunshine, the Rhine may wear a grander, nobler aspect, and to such I leave it.