I was on the Pennsylvania five minutes before she left N. Orleans, and I must tell you the truth, Mollie--three hundred human beings perished by that fearful disaster. Henry was asleep--was blown up--then fell back on the hot boilers, and I suppose that rubbish fell on him, for he is injured internally. He got into the water and swam to shore, and got into the flatboat with the other survivors.--[Henry had returned once to the Pennsylvania to render assistance to the passengers. Later he had somehow made his way to the flatboat.]--He had nothing on but his wet shirt, and he lay there burning up with a southern sun and freezing in the wind till the Kate Frisbee came along. His wounds were not dressed till he got to Memphis, 15 hours after the explosion. He was senseless and motionless for 12 hours after that. But may God bless Memphis, the noblest city on the face of the earth. She has done her duty by these poor afflicted creatures--especially Henry, for he has had five--aye, ten, fifteen, twenty times the care and attention that any one else has had. Dr. Peyton, the best physician in Memphis (he is exactly like the portraits of Webster) sat by him for 36 hours. There are 32 scalded men in that room, and you would know Dr. Peyton better than I can describe him, if you could follow him around and hear each man murmur as he passes, “May the God of Heaven bless you, Doctor!” The ladies have done well, too. Our second Mate, a handsome, noble hearted young fellow, will die. Yesterday a beautiful girl of 15 stooped timidly down by his side and handed him a pretty bouquet. The poor suffering boy's eyes kindled, his lips quivered out a gentle “God bless you, Miss,” and he burst into tears. He made them write her name on a card for him, that he might not forget it. Pray for me, Mollie, and pray for my poor sinless brother. Your unfortunate Brother, SAML. L. CLEMENS. P. S. I got here two days after Henry. It is said that Mark Twain never really recovered from the tragedy of his brother's death--that it was responsible for the serious, pathetic look that the face of the world's greatest laugh-maker always wore in repose. He went back to the river, and in September of the same year, after an apprenticeship of less than eighteen months, received his license as a St. Louis and New Orleans pilot, and was accepted by his old chief, Bixby, as full partner on an important boat. In Life on the Mississippi Mark Twain makes the period of his study from two to two and a half years, but this is merely an attempt to magnify his dullness. He was, in fact, an apt pupil and a pilot of very high class.