ANTIQUES ROADSHOW host Mark L. Walberg meets appraiser Eric Silver at Miami's Wolfsonian Museum to examine its large collection of World's Fair objects. Highlights include: a rare, Qing Dynasty (early 18th-century) vase; a 1956 Gretsch Chet Atkins Model 6120 guitar; and a charming oil painting by popular Victorian artist John George Brown, valued at $40,000 to $50,000.