Montgomery County Council member Isiah Leggett pleaded yesterday with those involved in the debate on Silver Spring's future to discuss the issues calmly and to avoid "the height of hysteria."

Leggett's comments, directed at developer Lloyd Moore and citizens groups opposed to his plans for a $250 million commercial-residential project, came at a meeting about preserving downtown Art Deco buildings Moore wants to demolish.

The meeting, arranged by the Allied Civic Group, became controversial when two businessmen who had been asked to speak about preservation said that Moore had used threats of legal action in an apparent attempt to silence them.

Bethesda developer John Westbrook and Frederick businesssman G. Bernard Callan said they each received a letter from Moore's attorney saying they "could be held financially responsible" if their actions jeopardized Moore's project.

Moore and William Kominers, a lawyer with the firm of Linowes & Blocher who wrote the letter, denied that the correspondence was intended as a threat. Moore had said he wished merely to get opinions on his plans for development.

Council member Bruce Adams yesterday called the Kominers letter "heavy-handed and unfortunate." Leggett did not specifically cite the letters but twice asked for an open debate with no emotion.

Moore told Leggett he agreed. Moore also said he is revising his plans, trying to incorporate some suggestions made by business and community groups. Moore would not discuss specifics but said to wait for the formal filing of his proposal, expected in about a month.