Wolfert Van Couwenhoven visited New Amsterdam in 1625 but apparently was unimpressed. He left town and went home to the Netherlands, only to return five years later and purchase a large tract of land on Long Island. He probably never imagined that his odyssey would be immortalized, but there it is, nearly 400 years later, at the New York Public Library.

The library’s extensive genealogical collection has just been enormously enhanced by the gift of 75,000 volumes, 30,000 manuscripts and 22,000 reels of microfilm from the New York Genealogical and Biographical Society.

Faced with a dwindling endowment, the members-only G & B, as it is known, sold its four-story building on East 58th Street in Midtown Manhattan last year for $24 million. It bought an office condominium in Midtown where it will now focus on grant-giving, tours, lectures and other means of encouraging genealogical research. One of the first grants was about $1 million to the library for a four-person staff to process and catalog the G & B collection within two years.

“The G & B wanted a place where the members would have access and where the collection would be taken care of,” said David S. Ferriero, the Andrew W. Mellon director of the New York Public Libraries.