PARK THEATRE--MR. FORREST.--TWO succeeding engagements of Mr. FORREST, have given us an opportunity of witnessing his efforts in all of his old, and in some (to him) new characters. Othello, Damon, Richard III., Metamora, Spartacus, Lear, Carwin, in the 'Orphan of Geneva,' and even Hamlet, have in turn been presented, through the impersonations of Mr. Forrest. Among these, there are some characters which long ago he made his own, and which have not since found any other representative. Such are Metamora, Spartacus, and perhaps Damon; Othello and Lear, too, had been previously attempted by Mr. Forrest, and found among his many friends enthusiastic admirers. This last engagement, however, has presented this gentleman in two new characters, Richard and Hamlet. Of the first of these, it shall be our province to speak in this paper. Mr. Forrest has challenged criticism upon his conception of the character of the Duke of Gloster, by his remarks contained in a published letter to a friend, written during his English visit. In this letter he boldly affirms, that the ideas which EDMUND KEAN always held of the personage which he represented as the Duke of Gloster, were erroneous, in one great particular, and that therefore _he_ should portray the crook-backed tyrant in a light quite different from that in which Kean presented him. This error of Kean consisted, it seems, in supposing the royal cut-throat to have been a too _serious_ villain; in presenting the early part of his career in a shade too sombre. According to Mr. Forrest, the wily duke was rather inclined to be jocose in his butcheries; and he should therefore, in his personation of the character, make the jester a sort of _basso-relievo_ to the hard, black surface of his marble heart.