Nineteenth-Century art, a field once relegated to the bottom of the auction barrel, has become a hot item. Christie's New York last week set records for seven 19th-Century European artists. Giovanni Boldini's painting, "The Summer Stroll," sold for $1.65 million; Alfred Stevens' "In the Country" went for $462,000; Jean Beraud's "Une Avenue Parisienne" fetched $418,000. Also among the top 10 items in the sale, Sir Frank Dicksee's "Scenes From Romeo and Juliet" brought $264,000, Montague Dawson's "Aeriel and Taeping"(CQ) sold for $176,000, Martin Rico y Ortega's "The Grand Canal, Venice" was knocked down at $165,000 and Odoardo Borrani's "A Promenade in the Garden" brought $154,000. The Feb. 23 auction totalled $8.1 million in sales, the largest total to date for a 19th-Century sale at Christie's New York. "The top lots show strength in the market," said Christie's Polly Sartori, who noted that Boldini's 1873 masterwork far surpassed his previous record of $715,000, set just a year ago at Christie's.