The universe is not only queerer than we imagine, it is queerer than we can imagine."

That was the point of view of the late distinguished British biologist J.B.S. Haldane, and it lives on in the diverse researches of the International Fortean Organization (INFO), which held its annual convention over the weekend at American University.

Some 200 "Forteans" (their worldwide membership is around 500), who take their name from the early 20th-century journalist and scientific maverick Charles Fort, heard reports on topics ranging from "Champ - the Lake Champlain Monster" and "Another Look at Atlantis", to "UFO Information from FBI Files" and 'Phantom Aircraft of 1915." Their common concern are those unexplained phenomena to which the scienific establishment can't - or won't - pay attention.

"We're curious people," said one member, a technical writer for an engineering firm. "Or, perhaps I should say, we have curiosity. We don''t have the answers - we just want to call people's attention to these things. For instance, you're farmer. One day a fifty-pound chunk of ice falls into your field. We have reports like this going back to before airplanes. You could call us jealous guardians of the unexplained."

Another Fortean, an electrical engineer, adds that INFO's chief interest is preserving records of such untoward occurences and not in advancing explanatory theories. He calls this principle the "antithesis" of such theorizers as Erich Vonn Daeniken, author of "Chariot of the Gods," who's followers held a convention last week in Chicago. "There is an adulation for Von Daeniken. These people are totally addicted to the theory that ancient astronauts visited the earth, as if all the evidence proves this."

Among Sunday's speakers was a young naval research physicist, Bruce Maccabee. He has gained access to FBI files which he claims, show that in the 40s and 50s both the FBI and the Air Force conducted extensive investigations into UFO sightings. Though the FBI soon withdrew from the field, "as early as 1947 Air Force Intelligence concluded that UFO's were real," he said.

In 1969, however, the Air Force officially closed its book on UFO's with the publication of the controversial "Condon Report" and the termination of its Project Blue Book, - its 21-year probe of UFOs - with the conclusion that UFOs are earthly phenomena.

At the same time, the Air Force admitted that some 10 percent of UFO sightings "are indeed strange and mysterious, impossible . . . to explain." And there were charges by scientists originally involved in the Air Force investigation that it was the product of scientific bias - the work of "non-believers."

Proceeding in the Fortean spirit of keeping an open - though skeptical - mind, Maccabee is trying to reopen the "closed book" on UFOs.

Another of Sunday's speakers was a bearded 26-year-old Canadian who calls himself Mr. X. He also calls himself "an unsuccessful writer and inventor," and publishes a review of unexplained phenomena titled "Chaos - The Review of the Damned" (a reference to Charles Fort's description of such phenomena as "damned" by the scientific community).

Lately he's been pouring over old newspaper accounts, unearthing possible UFO sightings during the first World War ("Phantom Aircraft of 1915"). But his interests encompass the entire range of unexplained occurance - the Bermuda Triangle, the Loch Ness Monster and poltergeists. He is quick to note that the scitific establishment "has always showed resistance to new ideas - to things that it was afraid to explain . . .", and to remind you that "before 1919, the size of the universe was considered to be the size of the Milky Way." He reminds you that even the revolutionary Einstein might be baffled by contempary physics.

The Forteans are not without humor about their quixotic enterprise - an official leaflet offered free tickets to an exhibition of "Little Green Men." But a visitor to their convention could not help observing that a door left open to new ideas will also admit the pure eccentric. Which might describe the jovial executive director of the Texas-based "Association to Push Gravity, a retired civil servant, who proposed to pierce the "Mysteries of Gravity" with his notion that the force that keeps man rooted firmly on the ground is not a pulling one, but rather the mass of the stars - of all matter - pressing down upon him.

But when another Fortean later seemed doubtful about this theory, it was with the gentlest incredulity that he averred, "We are a skeptical organization."