The winged romantics Cupid and Psyche, poised on a wall of the Corcoran Gallery foyer last night, would have smiled at the company they kept.

In the foyer were physicians, chemists, engineers and mathematicians from a firm called Operations Research Inc., which last month bought a corporate membership in the Corcoran so they could throw their office party there.

The party, for some 1,000 guests, marked the 25th anniversary of the founding of the organization, based in Silver Spring, the first private operations research firm in the area, its members claim.

Virtually all of their work is government contracted, and is considered "systems analysis": For the Coast Guard they analyze why ships run aground; for NASA they work on satellite designs and help figure out what to do with their space shuttle ("That's a big problem for NASA," one scientist says).

And, although in the infant days of the 380-person company they may have had a mathematician or two who once broke codes for the government during a war, they are not - and never have been - former spies, according to ORI President Harvey Kushner. In fact, the mere question sends Kushner into a cold sweat.

"We're not in the spook business," Kushner said.

"The people we hired pretty much cause-and-effect types," said co-founder Emory Cook, who left the company 10 years ago. "They were the kind of guys who could do a problem when they had to."

Cook started the organization because "the world needed some problem-solving." he said. The problems are different now, he reflected. "Then if you had a problem you could go to one person to get it solved. Now, you have to go to 100."

As the evening wore on, guests sat on the marble steps of the Corcoran, some slipping off their shoes. Several musical groups entertained, but none was so spontaneous as "The Space Chords," a barbershop quartet composed of ORI aerospace engineer Joe Deskevich and Goddard Space Flight Center scientists Jack Libby, Jerry Hodge and Gil Mead. "We're the only NASA quartet NASA has," said Mead. CAPTION: Picture, Mr. and Mrs. Harvey Kushner at last night's ORI party; by Harry Naltchayan - The Washington Post