Books: Uncle Sam as John Bull

THE NEW AMERICAN COMMONWEALTH by Louis Heren. 366 pages. Harper & Row. $7.95.

"The youth of America is its oldest tradition," Oscar Wilde quipped more than half a century ago. "It has been going on now for three hundred years."

Louis Heren, chief Washington correspondent for the Times of London, brings this geriatrics report up to date in a brisk spot checkup on the U.S. political system, loosely paralleling the classic study performed in The American Commonwealth (1888) by another sympathetic Englishman, Lord Bryce. Measured by the age of its continuous governing institutions, Heren judges the U.S. to be the second oldest country...