We struck the creek just without the limits of the city, and the first object that attracted our attention was “Decatur’s tomb.” This memorial of a departed naval hero occupies the summit of a picturesque hill, and is shaded from the sun by a brotherhood of handsome oak trees. It is built of bricks (which are painted white), and resembles in shape a small Grecian temple without its columns, and is without any inscription. The remains of the commodore were originally deposited here, but his ashes have subsequently been removed to Philadelphia and deposited in his family vault. The land upon which this tomb is located is called Kalorama, and belongs to an estate originally owned by Joel Barlow, which fact is alone sufficient to give it a reputation; but it is somewhat more interesting to know that it was upon this spot of earth that Robert Fulton first tried his experiments while studying out the science of steam navigation. This was at the time when Barlow and Fulton were on the most intimate terms of friendship, and Kalorama was Fulton’s principal home. A gentleman residing in Georgetown informs us that he can remember the time when an old wooden shed was standing in the vicinity of Rock Creek, where Fulton tried many of his experiments; and we are also informed that the parlor walls of Kalorama were once ornamented with fresco paintings executed by Fulton at the request of his friend Barlow. Subsequently to that period and while yet a member of Barlow’s family, Fulton kept an account-book, in which he recorded all his business transactions, and that curious and valuable relic of the departed engineer is now in the possession of a citizen of Washington, by whose politeness we are privileged to gratify our antiquarian readers with a brief description of the account-book in question. It is of the size of an ordinary mercantile cash-book, and although only half filled with writing, it contains a record of business transactions occurring during the years 1809,-’10,-’11,-’12,-’13, and ’14. It seems to have been kept with little regard to method, but nevertheless contains a great variety of items which are quite valuable in a historical point of view. On a fly leaf, for example, we have the following record:— “1813. The dry-dock finished at the steamboat works in Jersey City on the 14th October. On that day, at 1 o’clock, the original North River steamboat entered for the first time, and I believe is the first vessel that has been in a dry-dock in the United States.”:— With regard to the name of the “original North River steamboat,” I am not certain; but on the same leaf with the above, I find the following memorandum:— “_Car of Neptune_—length of her bottom 157 feet; do. on deck 171 feet 6 inches; extreme width of the bottom 22 feet; do. on deck 26 feet.” With a view of showing the profitableness of the steam-boating business in the olden times, I append the following:— “Total number of passengers in the Raritan for 1809: