The representation of the play called "Ah Sin" at the Fifth Avenue Theatre yesterday evening afforded frequent gratification to a very large audience. The fact that a good many spectators grew perceptibly weary as the performance approached an end, and the still more significant fact that the audience left the house without making the slightest demonstration of pleasure when the curtain fell upon the last scene, may imply that the piece, as a whole, is scarcely likely to secure a really strong hold upon the favor of the public. But it is certain that there was much laughter and applause heard as "Ah Sin" progressed, and the causes of the merriment and plaudits appeared sufficiently numerous to give some vitality to the composition of which they are the principal element. It need hardly be said that Messrs. Bret Harte and Mark Twain's play is by no means a very dramatic or symmetrical work. Humorists, romance writers, and poets are never born and seldom become dramatists, and both authors of "Ah Sin" are now truing their 'prentice hand in seeking fame and fortune through the medium of the stage. "Ah Sin," however, is not so bad a piece as might have been anticipated. It has a plot, well-worn and transparent though it is at once discovered to be, and hence there is a reason for almost everything said or done during the disentanglement of the narrative. Its weakness lies in a paucity of striking events, in an almost invariable disregard of the absolute necessity of providing a strong tableau at the close of each act, and in a superabundance of dialogue, mainly coarse, and often inexcusably so, because it has not the excuse of being characteristic. Its merit is to be sought, firstly, in the somewhat novel personage who bestows his name upon the drama; secondly, as mentioned above, in its rather unexpected coherence, and, lastly, in the strange atmosphere into which it transports the listener. Most of the characters do not indeed differ in any essential traits from the everyday heroes and heroines of melodrama, but their language, their attire, and their surroundings breathe an air of freshness over the picture. M. Dennery might turn them into Frenchmen, Mr. Boucicault into Irishmen, and Mr. Daly into Massachusetts saints and sinners, but the charm of local color is of great weight in dealing with Messrs. Harte and Twain's joint production. And the character of Ah Sin has unquestionably originality and newness. The typical Chinaman, who acts, too, as a sort of deus ex machina, presents a variety of phases of Chinese humor, cleverness, and amusing rascality. His comical naiveté, his propensity to beg and steal, his far-seeing policy, thanks to which a happy denouement of this particular story is brought about, are happily illustrated. Naturally enough Ah Sin finally becomes a little monotonous; there is, however, so much idle gabble in he drama that his appearance is usually welcome. Of the serious business intrusted to the other personages there is, as we have said, more than a sufficiency. We shall, therefore, not waste much space upon the story of "Ah Sin." It turns upon the rascality of one Broderick, who all but murders Bill Plunkett--"the champion liar of Calaveras"--and then accuses York, a "gentleman miner," of the crime. Just as a committee of lynchers are about to act upon a verdict of guilty, Ah Sin fastens the guilt of the deed upon Broderick by the exhibition of the murderer's coat, which Broderick thought he had long since done away with, and Plunkett being subsequently brought into court safe and sound, the piece terminates happily. If Messrs. Harte and Twain had handled all their material as deftly as in the first act, "Ah Sin" would have been a very praiseworthy effort. Although the longest of the four divisions of the play, the first awakens interest and closes with an ingenious surprise. The second act, concluding with an attempt to arrest Ah Sin on a charge of murder, and with the flight of the "vigilantes," who are routed by Ah Sin expectorating water upon them as though he were dampening linen in the Chinese fashion, is tedious, and the third drags sadly. The vicissitudes of a trial before a "border jury" enliven the fourth act, which would round off the piece very neatly if something besides a scene of extravagant joy worthy a burlesque prefaced the fall of the curtain. "Ah Sin" was capitally acted, last night, and admirably placed upon the stage. Mr. Parsloe's Chinaman could scarcely be excelled in truthfulness to nature and freedom from caricature. Mr. P. A. Anderson pictured with marked force and freedom from conventionality Bill Plunkett. Mr. Davidge, as the "chief of the Vigilantes," distinguished himself especially in the trial scene, and the remaining male roles found suitable interpreters in Messrs. Crisp, Collier, Weaver, Varrey, and Vining Bowers. Among the softer sex Mrs. Gilbert bore off the honors, in a new rival of Mrs. Malaprop--Mrs. Plunkett by name. Much of the language put into Mrs. Plunkett's mouth is far from refined, but some of it is funny, though the character and her peculiarities are become well-nigh threadbare. A still more offensive type of femininity--Caroline Anastasia Plunkett--was represented by Miss Edith Blande with becoming masculinity. Miss Dora Goldthwaite endowed Shirley Tempest with appropriate personal charms, and finally, Miss Mary Wells did all that could be done with Mrs. Tempest. After the third act, Mr. Clemens stepped before the footlights, and delivered an address in his familiar vein, but with less than his wonted felicity of style and more than his wonted drawl. "Ah Sin" is to be repeated at the Fifth Avenue Theatre every evening until further notice.