Mr. Seba Smith has become somewhat widely celebrated as the author, in part, of the “Letters of Major Jack Downing.” These were very clever productions; coarse, but full of fun, wit, sarcasm and sense. Their manner rendered them exceedingly popular, until their success tempted into the field a host of brainless imitators. Mr. S. is also the author of several poems; among others, of “Powhatan, a Metrical Romance,” which we do not very particularly admire. His MS. is legible, and has much simplicity about it. At times it vacillates, and appears unformed. Upon the whole, it is much such a MS. as David Crockett wrote, and precisely such a one as we might imagine would be written by a _veritable_ Jack Downing; by Jack Downing himself, had this creature of Mr. Smith’s fancy been endowed with a real entity. The fact is, that “The Major” is not _all_ a creation; at least one half of his character actually exists in the bosom of his originator. It was the Jack Downing half that composed “Powhatan.” [Illustration: signature of Jos. Hopkinson] Judge Hopkinson’s hand is forcible, neat, legible, and devoid of superfluity. The characters have much slope, and whole words are frequently run together. The lines are at equal distances, and a broad margin is at the left of the page, as is the case with the MSS. of Judge Marshall, and other jurists. The whole is too uniform to be picturesque. The writing is always as good at the conclusion, as at the commencement of the epistles—a rare quality in MSS., evincing _indefatigability_ in the writer. [Illustration: signature of Alexander Slidell] Lieutenant Slidell, some years ago, took the additional name of Mackenzie. His reputation, at one period, was extravagantly high—a circumstance owing, in some measure, to the _esprit de corps_ of the navy, of which he is a member, and to his private influence, through his family, with the Review-cliques. Yet his fame was not altogether undeserved; although it cannot be denied that his first book, “A Year in Spain,” was in some danger of being overlooked by his countrymen, until a benignant star directed the attention of the London bookseller, Murray, to its merits. Cockney octavos prevailed; and the clever young writer who was cut dead in his Yankee habiliments, met with bows innumerable in the gala dress of an English _imprimatur_. The work now ran through several editions, and prepared the public for the kind reception of “The American in England,” which exalted his reputation to its highest pinnacle. Both these books abound in racy description; but are chiefly remarkable for their gross deficiencies in grammatical construction. Lieut. Slidell’s MS. is peculiarly neat and even—quite legible, but altogether too petite and effeminate. Few tokens of his literary character are to be found, beyond the _petiteness_, which is exactly analogous with the minute detail of his descriptions. [Illustration: signature of Francis Lieber]