Fillmore House, Newport, Rhode Island, September 13th.—We left New York on Thursday afternoon, and embarked in a Brobdingnagian steamboat, which it would not be very easy to describe. The cabin is on the upper deck, so that at either end you can walk out on to the stern or bow of the vessel; it is about eleven feet high, and most splendidly fitted up and lighted at night with four ormolu lustres, each having eight large globe lights. We paced the length of the cabin and made it 115 paces, so that walking nine times up and down made a nice walk of a mile. The engine of the steamboat in America rises far above the deck in the centre of the vessel, so this formed an obstruction to our seeing the whole length, unless on each side of the engine, where a broad and clear passage allowed a full view from end to end; but instead of taking away from the fine effect, the engine-room added greatly thereto, for it was divided from the cabin, on one side, by a huge sheet of plate glass, through which the most minute workings of the engines could be seen. There was in front a large clock, and dials of every description, to show the atmospheric pressure, the number of revolutions of the wheel, &c. This latter dial was a most beautiful piece of mechanism. Its face showed six digits, so that the number of revolutions could be shown up to 999,999. The series of course began with 000,001, and at the end of the first turn the nothings remained, and the 1 changed first into 2, then into 3, &c., till at the end of the tenth revolution the two last digits changed together, and it stood at 000,010, and at the 1,012th revolution it stood at 001,012.

To go back to the saloon itself; the walls and ceiling were very much carved, gilt, and ornamented with engravings which, though not equal to our Albert Durers, or Raphael Morghens at home, were respectable modern performances, and gave a drawing-room look to the place. The carpet was gorgeous in colour, and very pretty in design, and the arm-chairs, of which 120 were fixtures ranged round the wall, besides quantities dispersed about the room, were uniform in make, and very comfortable. They were covered with French woven tapestry, very similar to the specimens we bought at Pau. There were no sofas, which was doubtless wise, as they might have been turned to sleeping purposes. Little passages having windows at the end, ran out of the saloon, each opening into little state cabins on either side, containing two berths each, as large as those on board the Africa, and much more airy; but the wonderful part was below stairs. Under the after-part of the saloon was the general sleeping cabin for the ladies who could not afford to pay for state cabins, of which, however, there were nearly a hundred. Our maid slept in this ladies' cabin, and her berth was No. 306, but how many more berths there may have been here we cannot tell. This must have occupied about a quarter of the space underneath the upper saloon. The remaining three quarters of the space constituted the gentlemen's sleeping cabin, and this was a marvellous sight. The berths are ranged in four tiers, forming the sides of the cabin, which was at least fourteen feet high; and as these partook of the curve of the vessel, the line of berths did the same, so as not to be quite one over the other. There were muslin curtains in front of the berths, forming, when drawn, a wall of light floating drapery along each side of the cabin, and this curved appearance of the wall was very pretty; but the prettiest effect was when the supper tables were laid out and the room brilliantly lighted up. Two long tables stretched the whole length, on which were placed alternately bouquets and trash of the sweet-cake kind, though the peaches, water-melons, and ices were very good, and as we had luckily dined at New York, we were satisfied. The waiters were all niggers, grinning from ear to ear, white jacketed, active, and clever, about forty strong. The stewardesses, also of African origin, wore hoops of extravagant dimensions, and open bodies in front, displaying dark brown necks many of them lighted up by a necklace or diamond cross, rivalling Venus herself if she were black. They were really fearful objects to contemplate, for there was a look of display about them which read one a severe lesson on female vanity, so frightful did they appear, and yet rigged out like modern beauties. It was the most lovely afternoon conceivable, and we stayed on deck, sometimes on the bow and sometimes on the stern of the vessel, till long after dark. We preferred the bow, as there was no awning there, and the air was more fresh and invigorating.

The passage through Long Island Sound was like a river studded on both sides with villas and green lawns, something like the Thames between Kingston and Hampton, but much wider, and with higher background, and altogether on a larger scale. When, owing to the darkness, we lost sight of these, they were replaced by lighthouses constantly recurring. This huge Leviathan, considerably longer than the Africa, proceeded at the rate of about eighteen miles an hour, going half-speed only, on account of the darkness of the night. The full speed was twenty-four miles an hour, and remember this was not a high-pressure engine. After proceeding through this narrow channel for about 120 miles, we again entered the Atlantic, but speedily reached the narrow inlet which extends up to this place. You may wonder at our having been able to make such minute observations upon the saloon, &c.; but having tried our state cabin, and not relishing it, we paced up and down the saloon, and occupied by turns most of its 120 chairs, till three o'clock in the morning brought us to the end of our voyage. There was no real objection to the cabin, beyond the feeling that it was not worth while to undress and lie down for so short a time; besides which, papa was in one of his fidgetty states, which he could only relieve by exercise.

But how now to describe Newport? Papa is looking out of the window, and facing it is an avenue of trees running between two lawns of grass as green as any to be seen in England, though certainly the grass is coarser than at home. In these lawns stand houses of every shape and form, and we, being au troisième have a distant view of the sea, which looks like the Mediterranean studded with ships. As this place (the Brighton of New York) stands on a small island, this sea view is discernible from all sides of the house. We walked yesterday a long way round the cliffs, which are covered with houses far superior to the average villas in England, the buildings being of a brilliant white and sometimes stone colour, and of elaborate architecture, with colonnades, verandahs, balconies, bay windows of every shape and variety, and all built of wood. The churches are some of them very beautiful, both Gothic and Grecian. A Gothic one to which we went yesterday afternoon, was high, high, high in its decorations, but not in the least in the doctrine we heard, which was thoroughly sound on "God so loved the world," &c. The fittings up were very simple, and the exterior of the church remarkable for the grace and simplicity of its outline; for being, like the houses, built entirely of wood, elaborate carving cannot be indulged in.

The church which we went to in the morning offered a great contrast to this, the interior being fitted up with high old-fashioned pews, like many a village church at home; but besides this, a further interest attached to Trinity Church, as being the one in which Dean Berkeley used to preach, and from its remaining unaltered in its internal appearance from what it was in his days. The pulpit is still the same, and there is still in the church the organ which he presented to it, at least the original case of English oak is there, and part of the works are the same, though some pipes have lately been added. Independently of Trinity Church, the town of Newport has many associations connected with Bishop Berkeley's memory, the place where he lived, and where he wrote his "Minute Philosopher" being still pointed out, as well as the spot on the beach where he used to sit and meditate. The most striking buildings, however, are the hotels, one of which, the "Ocean House," is the largest building of the kind we have ever seen. It has very much the appearance of the huge convents one sees in Italy, and, standing on the top of the cliffs, it has a most remarkable effect. There are some very good streets, but the greatest part of the town consists of detached houses standing in gardens. There are very few stone buildings of any kind. The hotel we are in is not the largest, but is considered the best, and in the height of the season the place must be very gay.

The next, perhaps the greatest, feature here is the bathing. There are three beaches formed round a succession of points, the whole forming a lovely drive on dry hard sand; and such a sun as we gazed upon yesterday setting over these distant sands passes description. On the first of these beaches are ranged more than a hundred bathing machines at about a hundred yards above high-water mark, looking like sentry boxes on a large scale, with fine dry sand between them and the sea. We went down on Saturday to see the bathing, which is here quite a public affair; and having fixed our eyes on a machine about a dozen yards off, we saw two damsels enter it, while a young gentleman, who accompanied them went into an adjoining one. In a few minutes he came out attired in his bathing dress and knocked at the ladies' door. As the damsels were apparently not ready, he went into the water to wait their coming, and in due time they sallied forth dressed in thick red baize trowsers and a short dress of the same colour and material, drawn in at the waist by a girdle. The gentleman's toilet was coloured trowsers and a tight flannel jacket without sleeves. He wore no hat, but the ladies had on very piquante straw hats trimmed with velvet, very like the Nice ones, to preserve them from a coup de soleil. They joined each other in the water, where they amused themselves together for a long time; a gentleman friend's presence on these occasions is essential, from the Atlantic surf being sometimes very heavy; but the young gentleman in question did not enact the part of Mr. Jacob, of Cromer, not being professional. The number of bathers is generally very great, though now the season being nearly over there are not many, but there were still enough to let us judge of the fun that is said to go on.

There are few guests in this house now. A "hop" was attempted on Friday evening in the entrance hall, but the unhappy musicians exerted themselves in playing the Lancers' Quadrilles and all sorts of ugly jerking polkas without success, although an attempt at one quadrille, we were told, was made after we had retired for the night. The table d'hôte toilettes here now are much quieter than they were at Westpoint, there being but two short sleevers yesterday at our two o'clock dinner. There is a large and handsome public drawing-room, where we can rock in rocking chairs (even the bed-rooms have them), or pass an hour in the evening. We are waited on at dinner by twelve darkies, as the niggers are called, marshalled by a head waiter as tall as papa and as black as his hat. A black thumb on your plate, as he hands it to you, is not pleasant. The housemaids are also niggeresses, and usually go about in coloured cotton sun bonnets. I now leave off, as we start for Boston in an hour.

Boston, 14th September, 1858.—We reached this yesterday, and were looking for William all the evening, but were disappointed at his non-appearance. He arrived here, however, at three this morning by the steamer, and is now recounting his adventures; he enjoyed himself very much, and looks all the better for his trip.

I ought to tell you of a few Yankee expressions, but I believe the most racy of them are used by the young men whom we do not come across: "I guess" is as common as "I think" in England. In directing you on any road or street, they tell you always to go "right away." If you do not feel very well, and think you are headachy, and that perhaps the weather is the cause, you are told you are "under the weather this morning." An excellent expression we think; so truly describing the state papa is often in when in dear old England. Then when you ask for information on any subject, the answer is frequently, "I can't say, sir, for I am not posted up on that subject." I asked an American gentleman, who was walking with us last night, not to walk quite so fast, and he answered, "Oh, I understand; you do not like that Yankee hitch." "Yankee" is no term of offence among themselves. Our friend certainly made use of the last expression as a quotation, but said it was a common one. They will "fix you a little ginger in your tea, if you wish it;" and they all, ladies and gentlemen, say, Sir, and Ma'am, at every sentence, and all through the conversation, giving a most common style to all they say; although papa declares it is Grandisonian, and that they have retained good manners, from which we have fallen off.

I reserve my description of the journey here, and of this town, for my next letter.