This was no ordinary party that the Corcoran Gallery of Art threw for its outgoing director, Peter Marzio. It was a benefit to help defray the cost of its new climate-control system.

"Peter's going-away party and air-conditioning ball," as Michael Botwinick, director of the Brooklyn Museum of Art and Marzio's successor, described it.

A fitting goodbye, perhaps, for the man whose four years on the job saw a substantial upswing in the fiscal state of the Corcoran. There was some talk of that last night, but mostly there were good wishes for Marzio -- who leaves to direct the Houston Museum of Fine Arts -- and his wife, Frances.

"We're going to miss him terribly," said Librarian of Congress Daniel J. Boorstin, who recommended his former research assistant, Marzio, to the Corcoran's trustees when they were seeking a new director four years ago. "He's part of Washington for us."

"I'll miss him very much," said the Smithsonian Institution's Charles Blitzer. "But I like Michael Botwinick very much. The only thing I feel sorry for is the Brooklyn Museum." Then he had another thought about Botwinick and Marzio (38 and 39 years old, respectively.) "Seems like everyone is 38. I suddenly realized when I came here 17 years ago, I was 38."

"In a way we were daring," said Corcoran board chairman David Lloyd Kreeger, referring to hiring Marzio, who had never directed a museum before the Corcoran, "but never wrong. It was one of the most brilliant decisions the Corcoran had ever made."

One estimate had the number of guests at 300. ("There were four other things we were competing with," said Julie Folger, a member of the women's committee who was in charge of last night's event.) Still, this was a rather low-key event in the lofty atrium which, at least once each year (during the Corcoran Ball), turns into a giddy, circusy pageant of more than 1,000 guests in full dress tuxedo and taffeta rustling past spangled dinner tables.

Last night guests simply wore silks and business suits and chatted as the Hot Federal Jazz Commission played. Olga Hirshhorn, widow of philanthropist Joseph Hirshhorn, came, and so did businessman Joe Allbritton. But the guests were mainly trustees and members of the museum community, and because they all knew each other, it was probably as close as a large museum could come to something intimate.

"It's the family," said trustee Gilbert Kinney. "Not a big fund-raiser." In fact, they will raise $15,000 to $20,000.

"It's a very warm, friendly group," said Botwinick. "That's part of Peter's legacy."

"Peter gave me the bad news about his leaving when I was in Paris," said Kreeger. "In a futile effort to persuade him to change his mind and in an effort to get Houston to give him more time with us, I ran up a $500 phone bill. But we can't be too greedy. We've had him for four years. I don't know why he wants to go to Houston, between you and me," Kreeger said to the clustered guests. "Houston only has two seasons -- the hot season and the unbearable season."

As a going-away gift, the women's committee presented the Marzios with a white earthenware cookie jar in the likeness of the Corcoran Museum. It was the work of local ceramicist Eve Watts.

Marzio thanked the trustees for their work, their friendship and most of all the museum. "The great joy of being director of the Corcoran is those five galleries upstairs," he said. He warned against being complacent about the financial state of the Corcoran and admonished his listeners to keep working on it. "If you succeed," he said, "the '80s will be the Corcoran decade--and it's about time."