These days, “musical piracy” can mean anything from illegal downloads to bootleg compact discs pressed in China. But back in 1878, the smash success of the Gilbert and Sullivan operetta “HMS Pinafore” resulted in a flurry of unauthorized “pirate” productions in the United States. The two resourceful Englishmen decided the best way to put a stop to it was to premiere their next collaboration in New York, thereby establishing its copyright under American law. And so, on today’s date in 1879, it was Arthur Sullivan himself who conducted the pit orchestra of the Fifth Avenue Theater in Manhattan for the first full performance of their latest creation, entitled, perhaps not coincidentally, “The Pirates of Penzance.” The New York Times review was glowing in its praise, but did point out that the new work was strikingly similar to “Pinafore,” but opined, “There is genuine musical merit in several of the numbers,” and, “A chorus of policemen was the most musically humorous number of the evening, and provoked more amusement than anything else... In response to repeated calls, the author and composer appeared before the curtain and bowed their acknowledgments.”