Adding to speculation about how the worldwide economic downturn will affect next month’s big auctions in New York, two sales abroad drew disappointing numbers. On Tuesday an auction of Islamic and Indian art at Christie’s in London sold just 47 percent of its 439 lots, Bloomberg News reported. The auction generated total sales of $18.1 million, according to Bloomberg; a similar auction at Christie’s in April generated $20.5 million from 282 lots. On Wednesday, Bloomberg reported, Sotheby’s in Hong Kong had lower sales than expected at the end of a five-day auction of Asian art. The auction was expected to yield about $257 million, but garnered $141.7 million from a sale of 1,700 items.