SS President President, the largest packet ship in the world, has disappeared with all 136 souls aboard in her third voyage. Last year, the British and American Steam Navigation Company, led by Junius Smith, 61, and Macgregor Laird, 43, famous for having made the Sirius cross the Atlantic ocean under steam for the first time three years ago, commissioned a second steamship for the line New York-Liverpool, after the successful 1850-ton British Queen (1838). She was the 2350-t