Dublin, Thursday, July 31, 1851.

Though the night was thick, the wind was light, and we had a very good passage across the North Channel, though our boat was very middling, and I was nearly poisoned by some of my fellow-sleepers in the gentlemen's cabin insisting that every window should be closed. O to be Pope for one little week, just long enough to set half a million pulpits throughout the world to ringing the changes on the importance, the vital necessity, of pure, fresh air! The darkness, or rather the general misapprehension, which prevails on this subject, is a frightful source of disease and misery. Nine-tenths of mankind have such a dread of "a draught" or current of air that they will shut themselves up, forty together, in a close room, car or cabin, and there poison each other with the exhalations of their mutual lungs, until disease and often death are the consequences. Why won't they study and learn that a "draught" of pure air will injure only those who by draughts of Alcoholic poison or some other evil habit or glaring violation of the laws of life, have rendered themselves morbidly susceptible, and that even a cold is better than the noxiousness of air, already exhausted of its oxygen by inhalation? Nothing physical is so sorely needed by the great majority as a realizing sense of the blessedness, the indispensable necessity of pure, fresh air.

We landed at Belfast at 5 this morning under a pouring rain, which slacked off two hours later, but the skies are still clouded, as they have been since Tuesday of last week, and there has been some sprinkling through the day.

Of course the Crops are suffering badly. Flax is a great staple of the North of Ireland, and three fourths of it is beaten flat to the earth. Wheat is injured and poor, though not so generally prostrate; Oats look feeble, and as if half drowned; some of these are, and considerable Barley is thrown down; Grass is light, much of it uncut, and much that is cut has lain under the stormy or cloudy skies through the last week and looks badly; only the Potatoes look strong and thrifty, and promise an ample yield. I shall be agreeably disappointed if Ireland realizes a fair average harvest this year.

Belfast is a busy, growing town, the emporium of the Linen Manufacture, and the capital of the Province of Ulster, the Northern quarter of Ireland. It seems prosperous, though no wise remarkably so; and I have been painfully disappointed in the apparent condition of the rural peasantry on the line of travel from Belfast to Dublin, which I had understood formed an exception to the general misery of Ireland. Out of the towns not one habitation in ten is fit for human beings to live in, but mere low, cramped hovels of rock, mud and straw; not one-half the families on the way seem to have so much as an acre of land to each household; not half the men to be seen have coats to their backs; and not one in four of the women and children have each a pair of shoes or stockings. And those feet!—if the owners would only wash them once a week, the general aspect of affairs in this section would be materially brightened. Wretchedness, rags and despair salute me on every side; and if this be the best part of Ireland, what must the state of the worst be?

From Belfast we had railroad to Armagh, 35 miles; then 13 miles by omnibus to Castle Blayney. We came over this latter route with ten or twelve passengers, and a tun or so of luggage on the outside of the Railroad Company's omnibus, with thirteen of us stowed inside, beside a youngster in arms, who illustrated the doctrine of Innate Depravity by a perpetual fight with his mother. Yet, thus overloaded we were driven the thirteen miles of muddy road in about two hours, taking at Castle Blayney another railroad train, which brought us almost to Drogheda, some 25 miles, where we had to take another omnibus for a mile or two, for want of a railroad bridge over the Boyne, thus reaching another train which brought us into Dublin, 32 miles. The North of Ireland is yet destitute of any other railroads than such patches and fragments as these, whereby I am precluded from seeing Londonderry, and its vicinity, which I much desired. At length we were brought into Dublin at half-past three o'clock, or in eight hours from Belfast, about one hundred and thirty miles.

The face of the country through this part of Ireland is moderately rolling, though some fair hills appear in the distance. The land is generally good, though there are considerable tracts of hard, thin soil. Small bogs are frequently seen, but no one exceeding a dozen acres; the large ones lying farther inland. Taking so little room and supplying the poor with a handy and cheap fuel, I doubt that these little bogs are any detriment to the country. Some of them have been made to take on a soil (by draining, cutting, drying and burning the upper strata of peat, and spreading the ashes over the entire surface), and are now quite productive.—Drainage and ridging are almost universally resorted to, showing the extraordinary humidity of the atmosphere. The Potato is now generally in blossom, and, having a large breadth of the land, and being in fine condition, gives an appearance of thrift and beauty to the landscape. But, in spite of this, the general yield of Ireland in 1851 is destined to be meager. There is more misery in store for this unhappy people.

We cross two small lakes some ten to fifteen miles north of this city, and run for some distance close to the shore of the Channel. At length, a vision of dwellings, edifices and spires bounds the horizon of the level plain to the south-west, and in a few minutes we are in Dublin.