Within the last fortnight we have progressed, as we say in this country, over about nine hundred and fifty miles of land and water.  We have gone up the Hudson, seen Trenton, the most beautiful, and Niagara, the most awful, of waterfalls.  As for Niagara, words cannot describe it, nor can any imagination, I think, suggest even an approximate idea of its terrible loveliness.  I feel half crazy whenever I think of it.  I went three times under the sheet of water; once I had a guide as far as the entrance, and twice I went under entirely alone.  If you fancy the sea pouring down from the moon, you still have no idea of this glorious huge heap of tumbling waters.  It is worth crossing the Atlantic to see it....  As I stood upon the brink of the abyss when I first saw it, the impulse to jump down seemed all but an irresistible necessity, and but for the strong arm that held mine fast I think I might very well have taken the same direction as the huge green glassy mountain of water that was pouring itself headlong into—­what no eye can penetrate.  It literally seemed as if everything was going down there, and one must go along with everything.  The chasm into which the cataract falls is hidden by dense masses of snowy foam and spray, rising in an everlasting creation of cloud up into the sky, and vailing the frantic fury of the caldron below, where the waves churn and tread each other underfoot in the rocky abyss that receives them, in darkness which the sun’s rays cannot penetrate nor the strongest wind for a moment disperse; a mystery, of which its thousand voices reveal nothing.  It is nonsense writing about it—­seeing and hearing are certainly, in this case, the only reasons for believing.  I think it would be delightful to pass one’s life by this wonderful creature’s side, and quite pleasant to die and be buried in its bosom....

We left that wonderful place a few days ago, steamed across Lake Ontario, came down the rapids of the St. Lawrence in an open boat, sang the Canadian boat song, and are now safe and sound, only half roasted, in his Majesty’s dominions.  Of all that we have seen, Niagara is, of course, the old object beyond all others, but we were delighted with the softness and beauty of a great deal of the scenery that we saw in traversing the State of New York—­one of twenty States, not the largest of the twenty, but large enough to hold England in its lap.

The rapids of the St. Lawrence, though, I believe, really rather dangerous to descend, have so little appearance of peril that I derived none of the excitement I had expected, and which a little danger always produces, from going through them.  Instead of shooting down long sheets of rushing water, which was what I expected, we were tossed and tumbled and shaken up and down, in the midst of a dozen conflicting currents and eddies, which break the whole surface of the river into short pitching waves, and dance about in frantic white whirligigs, like the circles of the bad nuns’ ghosts, in Meyerbeer’s devilish Opera....

Good-by, my dearest Emily.  I am always affectionately yours,