_Parras, May 28th._ I shall never forget the Buena Vista Camp, the night of the 23d and 24th, it was the night previous to our departure for this place; the guard was slow in coming out, Montrose Graham was guard over my tent that watch, and as Simson called his guard to order, and faced me, where I had risen up to see who were changing, George Weed let his rifle fall. The cock was down on the nipple, contrary to a positive order; in falling, the head of the hammer struck the ground first, and, as if the trigger had been pulled, it went off. An exclamation came from either side, one "Mr. Audubon's killed," the other from me: "Who's hurt?" A groan from poor Graham was the answer. We were all hurry for lights and water, and the Doctor. All loved Graham, he was the handsome man of the original party of ninety-eight, just twenty-two, and the Captain of his tent, "The Hailstorm Mess," so called by Lieut. Browning, from its go-ahead principles. The ball had passed through his ancle, and both Drs. Perry and Trask said he could not go on for some weeks. So it was decided to leave his cousin, Molinear, with him, a more practical physician than most of his age, and as much money as we could spare, that they could follow us or return home, as seemed most judicious. Frank Carrol, as good a man as I ever wish on such an expedition, found accommodations for Graham, and remained with him at Saltillo. How we parted from them only those can know who have been compelled to leave friends in a strange land. For several days our road continued over long hills, and parched valleys, and on the last day of this travel we had a most extraordinary view. We had climbed a hill, not more than three hundred feet high, but very steep, and reached a broad plain five or six miles wide, but much longer. On every side was a chain of sterile volcanic mountains; it was, for one view, most wonderful; it looked as if an immense lake, that threatened to cover the mountains, had suddenly been changed to earth. Crossing this plain and rounding one of the desolate peaks, we came to the hacienda of Don Emanuel Hivarez, who has five hundred peons at work. The water used for irrigation, without which nothing could be grown, is brought in an adobe aqueduct for several miles. It is an old settlement and very dirty, abounding in fleas and vermin of all descriptions. Yet when one comes to a hacienda with water all round, brought from some mountain stream, the contrast between the desolate land we have travelled and the exuberant luxuriance of vines, figs and magua gives a beauty which almost makes me, with my hatred of everything Mexican, admire our surroundings. Mocking-birds are all around us, and could I linger to explore, I have no doubt I could have added many new birds to my list, but with cholera hanging round, breaking out, in a mild form it is true, at every place we stop at, we must push on.