The person who assassinated Secretary SEWARD left behind him a slouched hat and an old rusty navy revolver. The chambers were broken loose from the barrel, as if done by striking. The loads were drawn from the chambers, one being but a rough piece of lead, and the other balls smaller than the chambers, wrapped in paper, as if to keep them from falling out.

On Friday evening, April 14, 1865, I was reading the evening paper in the reading-room of Willard's Hotel, at about 10 1/2 o'clock, when I was startled by the report that an attempt had been made a few minutes before to assassinate the President at Ford's Theatre. At first I could scarcely credit it, but in a few minutes the statement was confirmed by a number of people who came in separately, all telling the same story. About fifteen minutes previously I had parted with Mr. MELLER, of the Treasury Department, and he had retired to his room. Immediately on receiving this intelligence I notified him of it, and we together proceeded to the scene of the alleged assassination. We found not only considerable crowds on the streets leading to the theatre, but a very large one in front of the theatre, and of the house directly opposite, where the President had been carried after the attempt upon his life. With some difficulty I obtained ingress to the house. I was at once informed by Miss HARRIS, daughter of Senator HARRIS, that the President was dying, which statement was confirmed by three or four other persons whom I met in the hall; but I was desired not to communicate his condition to Mrs. LINCOLN, who was in the front parlor. I went into this parlor, where I found Mrs. LINCOLN, no other lady being present, except Miss HARRIS, as already mentioned. She at once recognized me, and begged me to run for Dr. STONE, or some other medical man. She was not weeping, but appeared hysterical, and exclaimed in rapid succession, over and over again: "Oh! why didn't he kill me? why didn't he kill me?" I was starting from the house to go for Dr. STONE, when I met at the door, Major ECKERT, of the War Department, who informed me he was going directly to STONE's house, STONE having already been sent for, but not having yet arrived. I then determined to go for Dr. HALL, whose precise residence I did not know. Upon inquiring of the crowd, I was told it was over FRANK TAYLOR's bookstore, on the avenue. This proved to be a mistake, and I was compelled to return to his actual residence on the avenue, above Ninth-street. I found the doctor at home and dressed, and he at once consented to accompany me. Arrived in the neighborhood of the house. I had great difficulty in passing the guard, and only succeeded at last in having the doctor introduced, admission being refused to myself. I returned to Willard's, it now being about 2 o'clock in the morning, and remained there until between 3 and 4 o'clock, when I again went to the house where the President was lying, in company with Mr. ANDREWS, late Surveyor of the port of New-York. I obtained ingress this time without any difficulty, and was enabled to take Mr. ANDREWS in with me. I proceeded at once to the room in which the President was lying, which was a bedroom in an extension, on the first or parlor floor of the house. The room is small, and is ornamented with prints -- a very familiar one of LANDSEER's, a white horse, being prominent directly over the bed. The bed was a double one, and I found the President lying diagonally across it, with his head at the outside. The pillows were saturated with blood, and there was considerable blood upon the floor immediately under him. There was a patchwork coverlet thrown over the President, which was only so far removed, from time to time, as to enable the physicians in attendance to feel the arteries of the neck or the heart, and be appeared to have been divested of all clothing. His eyes were closed and injected with blood, both the lids and the portion surrounding the eyes being as black as if they had been bruised by violence. He was breathing regularly, but with effort, and did not seem to be struggling or suffering.

The persons present in the room were the Secretary of War, the Secretary of the Navy, the Postmaster-General, the Attorney-General, the Secretary of the Treasury, (who, however, remained only till about 5 o'clock,) the Secretary of the Interior, the Assistant-Secretary of the Interior, myself, Gen. AUGER, Geo. HALLECK, Gen. MEIGS, and, during the last moments, Capt. ROBERT LINCOLN and Maj. JOHN HAY. On the foot of the bed sat Dr. STONE; above him, and directly opposite the President's face, an army surgeon, to me a stranger; another army surgeon was standing, frequently holding the pulse, and another gentleman, not in uniform, but whom I understood to be also an army surgeon, stood a good deal of the time leaning over the head-board of the bed.

For several hours the breathing above described continued regularly, and apparently without pain or consciousness. But about 7 o'clock a change occurred, and the breathing, which had been continuous, was interrupted at intervals. These intervals became more frequent and of longer duration, and the breathing more feeble. Several times the interval was so long that we thought him dead, and the surgeon applied his finger to the pulse, evidently to ascertain if such was the fact. But it was not till 22 minutes past 7 o'clock in the morning that the flame flickered out. There was no apparent suffering, no convulsive action, no rattling of the throat, none of the ordinary premonitory symptoms of death. Death in this case was a mere cessation of breathing.

The fact had not been ascertained one minute when Dr. GURLEY offered up a prayer. The few persons in the room were all profoundly effected. The President's eyes after death were not, particularly the right one, entirely closed. I closed them myself with my fingers, and one the surgeons brought pennies and placed them on the eyes, and subsequently substituted for them silver half-dollars. In a very short time the jaw commenced slightly falling, although the body was still warm. I called attention to this, and had it immediately tied up with a pocket handkerchief. The expression immediately after death was purely negative, but in fifteen minutes here came over the mouth, the nostrils, and the chin, a smile that seemed almost an effort of life. I had never seen upon the President's face an expression more genial and pleasing. The body grew cold very gradually, and I left the room before it had entirely stiffened. Curtains had been previously drawn down by the Secretary of War.

Immediately after the decease, a meeting was held of the members of the Cabinet present, in the back parlor, adjacent to the room in which the President died, to which meeting I, of course, was not admitted. About fifteen minutes before the decease, Mrs. LINCOLN came into the room, and threw herself upon her dying husband's body. She was allowed to remain there only a few minutes, when she was removed in a sobbing condition, in which, indeed, she had been during all the time she was present.

After completing his prayer in the chamber of death. Dr. GURLEY went into the front parlor, where Mrs. LINCOLN was, with Mrs. and Miss KINNEY and her son ROBERT, Gen. TODD, of Dacotah, (a cousin of hers,) and Gen. FARNSWORTH, of Illinois. Here another prayer was offered up, during which I remained in the hall. The prayer was continually interrupted by Mrs. LINCOLN's sobs. Soon after its conclusion, I went into the parlor, and found her in a chair, supported by her son ROBERT. Presently her carriage came up, and she was removed to it. She was in a state of tolerable composure at that time, until she reached the door, when, glancing at the theatre opposite, she repeated three or four times: "That dreadful house! -- that dreadful house!"