The New-York Historical Society, with a newly hired president and a conservative financier emerging as a board power, is shifting its focus from the city to more national concerns, stirring the objections of some historians and staff members.

Reflecting its new direction, the society has canceled an exhibition marking the centennial of Times Square and scaled back others with a local focus. It is mounting a $5 million exhibition on Alexander Hamilton, the most expensive in the history of the 200-year-old society, officials said.

The Hamilton exhibition, whose curator is Richard Brookhiser, a senior editor at the conservative National Review magazine, will be used for private receptions during this summer's Republican National Convention before opening to the public in September.

This shift in emphasis appears to signal the ascendance on the society's board of Richard Gilder, a stockbroker and a leading fund-raiser for Republican and conservative causes, who became a trustee a year ago.

It also seems to close off all possibility of the society's merger with the Museum of the City of New York, a long-contemplated move for two institutions that have struggled to attract visitors and revenue.

"If we were to focus on New York City, then we should merge," Mr. Gilder said in an interview yesterday."But there is a whole different mission for each of us."

Mr. Gilder, an avid collector of historical documents, whose holdings are on on permanent loan to the society, was one of three society trustees who together have contributed $2 million of $3 million raised so far for the Hamilton exhibition.

"There was nothing wrong," Mr. Gilder said, with the shows that have been canceled or scaled back."They just weren't really in the mainstream of American history. We want to focus on bigger things. We want to bring American history into every family."

Louise Mirrer, who became president of the society on June 1 after serving as executive vice chancellor of the City University of New York, said,"Hamilton is both the quintessential New Yorker and also absolutely emblematic of the direction this institution is moving in."

To coincide with the Hamilton exhibition's opening to the public on Sept. 10, the society plans to wrap the facade of its building at Central Park West and 77th Street in a huge $10 bill — the one bearing Hamilton's face. It will also set up a temporary cafe celebrating the country's founding fathers.

Mr. Gilder has been a major donor to conservative causes and candidates since the 1980's. He is on the board of the Club for Growth, a principal fund-raising engine of the conservative movement, and is chairman emeritus of the Manhattan Institute, a conservative research group....