FIRST, TO ALL Montrealers, we say: Pardonnez-nous. Even if only 3,923 of you showed up Monday night to watch your Expos lose 4-1 to the Florida Marlins, we understand the terrible emptiness left by a departing major league team. We feel your pain. We have felt your pain -- twice.

Which brings us to the second order of business: O happy day! It has been 80 years, almost to the day, since Washington won the World Series, and 33 years, almost to the day, since the Washington Senators played their last unruly game. Like most Washingtonians we've never wavered, for all those 33 years, in our belief that Washington is a major league city. Baseball belongs here. Welcome back!

But then, stashing our mitt once more in the closet and returning judiciously to our keyboard, we come to the third matter: Is it a good idea for the District of Columbia to build and own a baseball stadium, to the tune of something approaching a half-billion dollars? To be honest, that's not an easy call. It's clear that a pro football stadium, where a team plays just eight times a year, doesn't do a city much good as an economic engine. At the opposite end of the spectrum, few would disagree that MCI Center and its year-round attractions have done fine things for downtown Washington. A baseball stadium, which could attract 30,000 fans downtown 81 times per year, falls somewhere in between: not a sure thing but potentially a major plus for a neighborhood and city being rejuvenated.

No question Washington has deficiencies more compelling than the absence of baseball. If we could write the rules, baseball's owners would pay for the stadium -- as Wizards owner Abe Pollin heroically paid for MCI Center -- and the District would spend the $440 million on schools, libraries and parks. It is galling that a ballpark partly financed by taxpayers will swell the resale value of the Expos, thereby further enriching other major league team owners, a group toward which we harbor no particular fondness. But it's just as clear that baseball wouldn't come to Washington without a substantial public contribution, and Mayor Anthony A. Williams makes a persuasive case that other public needs won't be shortchanged to pay for the stadium. His plan calls for the city to borrow money to build the stadium, with annual repayments coming from rent the team will pay (starting at $3.5 million and increasing to $5 million and beyond after five years); taxes on tickets, hot dogs and other concessions (at least $11 million); and a business receipts tax on District-based businesses with a minimum annual revenue of $3 million (at least $21 million). If the numbers add up, the deal will be in line with what other cities and states have negotiated.

That "if" is but one question the D.C. Council should investigate. We don't object to Mr. Williams's putting this matter before a council that includes three lame ducks, because the deliberations must begin soon if a team is going to start playing in temporary quarters at Robert F. Kennedy Memorial Stadium in April. But the council should take such time as it needs to exercise real oversight; this is a deal the city will live with for many years. Are the city's attendance predictions realistic? If something goes wrong, who's on the hook? Will 1,100 parking spaces be enough? Is the Navy Yard Metro station equipped to handle big crowds, and, if it isn't, who will pay for its expansion? The council should draw on current economic data, consulting its own experts if need be. It should insist on publication of the contract between the city and Major League Baseball and any side agreements that may exist.

If the mayor can satisfactorily answer the council's questions, the deal will still be a gamble, but we think a gamble worth taking. Along with other plans in the works for South Capitol Street and the city's riverfronts, baseball could be a shot in the arm. But the council needn't let all the hoopla keep it from performing its due diligence.