The pride of the American Navy, the man-of-war _Princeton,_ Commodore Stockton in command, was lying in the Potomac just below Washington, on the morning of February 28, 1843. The day was beautiful, and the distinguished commander, who had known much of gallant service, had invited more than one hundred guests to accompany him on a sail to a point a few miles below Mount Vernon. Among the guests were President Tyler and two members of his Cabinet; Mr. Upshur, Secretary of State, and Mr. Gilmer, Secretary of the Navy; the widow of Ex-President Madison; Mr. Gardner, a prominent citizen of New York, and his accomplished daughter; Commodore Kennan; and a number of Senators and Representatives. Commodore Stockton was anxious to have his guests witness the working of the machinery of his vessel and to observe the fire of his great gun, his especial pride. Mr. Gardner and his daughter were guests at the Executive Mansion; and to the latter, the President--then for many years a widower --was especially attentive. Officers and guests were all in the best of sprits, and nothing seemed wanting to make the occasion one of unalloyed pleasure. Upon the return, and when almost directly opposite Mount Vernon, the company were summoned by the Commodore from the dinner table to witness the testing of the gun. Preceded by an officer, the guests were soon assembled in proximity to the gun. A place at the front was reserved for the President, but just as he was advancing, his attention was directed by his fair guest to some object on the shore. This for a moment arrested his progress, and prevented his instant death, for at this critical moment the gun exploded, causing the immediate death of more than twenty persons, and serious injuries to many others. Among the injured were Senator Benton and Commodore Stockton. The list of the dead included Secretary of State Upshur, Secretary of the Navy Gilmer, Commodore Kennan--one of the heroes of the second war with Great Britain,--and Mr. Gardner, the father of the lady whose timely interposition had caused the moment's delay which had saved the President from the terrible fate of his associates. Upon the return of the _Princeton_ to Washington the dead were removed to the Executive Mansion, and the day, so auspicious in the beginning, ended in gloom. Something in the way of romance is the sequel to that sad event. A few months later Miss Gardner, the fair guest of the President upon the ill-fated _Princeton,_ became his bride, and during the remainder of his term of office did the honors of the Executive Mansion.