A couple of years ago, when incoming Smithsonian Secretary Lawrence Small was looking around for space to house his private collection of Amazonian tribal art, he was picturing high ceilings, open spaces, long walls, maybe even skylights. He was thinking: Find and renovate an abandoned industrial loft. He was thinking: Create a private art gallery.

But Small quickly discovered, as have dozens of studio-seeking artists before him, that wishing for a loft is a lot easier than finding one in industry-poor Washington. He settled for convenience instead, deciding to convert a two-bedroom apartment just a few minutes' walk from his spacious house in Northwest Washington.

Small, then president of mortgage insurance giant Fannie Mae, gave up much of what he had dreamed of--namely, high ceilings, open spaces, long walls and skylights. But he seems satisfied by the trade-off. Scarcely a Saturday goes by that he doesn't stroll over to the converted apartment to fiddle and fuss for several hours with the installation of his wondrous assortment of feathery headdresses, masks, ceremonial costumes, baskets, arrows, earrings and so on.

The architectural team of Theodore Adamstein and Olvia Demetriou had much to do with Small's level of satisfaction. "I asked Theo and Olvia for a design that would be totally complementary to the art but not some imitation of the Amazonian world--not the Rain Forest Cafe," Small says.

Adamstein and Demetriou, best known for spirited designs of Washington-area restaurants such as Coco Loco and El Caribe, responded by transforming an ordinary apartment--low ceilings, clunky radiators, ribbon windows, interfering structural columns and all--into a quietly spectacular setting for the art. Because of the nine-foot ceilings and the quantity of art, the space remains slightly cluttered and claustrophobic--for an art gallery--but, hey, you can't have everything.

The architects started from scratch, tearing down all existing partitions and stripping the apartment to the bone. They were left with a long rectangular space with two smaller protruding rectangles, one shaped by a niche in the exterior wall and the other by a right-angled turn in the building's main corridor--a geometry that actually suited their needs quite well.

A decent foyer could be squeezed into the small rectangle near the apartment corridor, and the other projecting rectangle would serve for an office, bathroom and "emergency" bedroom with a king-size Murphy bed hidden behind a maple-wood wall. The largest of the spaces could be split down the middle to form a gallery on one side and services--kitchen, dining/conference room, shelves for books and small artifacts--on the other.

On the gallery side of this large rectangle there was, of course, one relatively long wall. But with a continuous horizontal window and three unmovable radiators, it looked as if it had been intentionally designed to discourage the display of art. Yet Adamstein and Demetriou turned this potential obstacle into a surface of exceptional allure and utility.

The trick is in the ingenious, built-in, maple-lined display cabinets evenly spaced along the wall. Each measures about 6 feet high by 4 feet wide and projects out from the wall about 3 feet. In between each cabinet is a display niche of the same size as the cabinet. Because both sides of the cabinet doors can be used to hang objects on, and these doors are capable of pivoting a full 180 degrees to cover the display niches, the wall is exceedingly flexible and dynamic. It looks good in any of several configurations--doors shut, partially open, fully open.

The character of the art clearly influenced the choice of subdued colors and materials. Small became interested in Amazonian tribal art during nearly three decades as an executive with Citibank/Citicorp in New York, where he was for many years in charge of the corporation's sizable operations in Brazil. What appeals to him particularly (as it would just about anyone) is the brilliant feather work of many ceremonial and functional objects--feathers with astonishing hues skillfully pieced together in patterns and forms of extraordinary beauty.

Obviously you wouldn't want the architecture to compete with such brilliance and delicacy. Thus, the surfaces and furniture are rather soft and warm-toned--walnut-wood tables and chairs, "figured" maple-wood walls and cabinets, dark burnished metals, a treated bamboo gallery floor, another floor of streaked, earth-toned slate. Yet you wouldn't call the resulting environment neutral or reticent. Rather, there is a subtle tension in the contrast between setting and art that somehow enhances both.

One of the appealing things about the architecture is the attention lavished on details. Every surface and fixture, it seems, has been lovingly crafted for a particular purpose. Translucent glass shelves, for instance, suspended with thin metal cables and lit from both above and below, are attractive in themselves and ideal for the display of small feathered objects. A swiveling pair of curved maple doors, separating office from gallery, has the presence of an abstract sculpture and, at a distance, also of a ritualistic mask.

The architects enlisted artists and craftsmen in their efforts to get things just right. Sculptor Lisa Scheer and muralist husband Hugh McKay were involved in patination of the metal surfaces, and it shows--several of the burnished wall mounts are as precise and pretty as abstract minimalist paintings, and at the same time make excellent backgrounds for animist Amazonian art. Craftsman Bradley Sanders shows a sensitive, almost magical touch in the metal armatures he designed for specific Amazonian objects.

One condition that no amount of architectural sleight of hand could completely disguise was the ceiling height--though Adamstein and Demetriou gave it a mighty try. Made of concrete, the ceiling was, to all practical purposes, impenetrable. Thus, no recessed lighting was possible. Instead, the architects designed a sequence of arched panels made of thin, silvery metal from which halogen lights could be hung--and it almost works.

Small's enthusiasm and involvement was important, the architects say. "He was a great client," according to Adamstein, "because he really cared and, at the same time, was open to ideas that were new to him." Small says he enjoyed the "intuitive" interchange with the designers. With his high-level business background, he quips, the danger was that anything he touched might turn out "looking like a wood-paneled men's club."

The job Small is about to take is not immune to architectural controversy, of course. With its museums on the Mall and elsewhere, the Smithsonian is the landlord of some of the best and most visibly placed buildings in all of the United States. It is impossible to say how or even whether the experience of seeing through the design of this small private gallery will influence Small's decisions vis-a-vis the Smithsonian buildings.

But at the very least, it is encouraging to see that he is adventurous and appreciates high quality. "People in Congress," he says, "should be excited about the need to fund better facilities" for the Smithsonian. "I would love to see those buildings shine."

CAPTION: Architects Theodore Adamstein and Olvia Demetriou turned a confined space into a splendid gallery for Smithsonian Secretary Lawrence Small's Amazonian art collection.

CAPTION: Lawrence Small lavished attention on functional details in the apartment in Northwest Washington he converted into a private gallery.