There is a special kind of magic that makes it possible to expand one's sense of space without adding an inch. The practitioners of this sorcery rely on paint and mirrors as well as more dramatic structural alterations to pierce walls and open vistas.

One of the oldest forms of illusion in residential design is the craft of trompe l'oeil ("fool the eye"), painting in which the surface is made to look like something it is not. From the Colonial period on, Americans have used this technique to create illusionary architecture -- painted images of columns and niches that gave walls deceptive depth. A variant of trompe l'oeil is the more common technique of marbling and graining. Colonial settlers with a little extra money would hire itinerant painters to decorate their mantels and baseboards -- and even doors -- to give the impression of a finer grade of wood or a "marble" mantelpiece. The Victorians were fond of using the same techniques to enhance their homes. About the turn of the last century, though, these art forms became mostly forgotten.

Now, architects and designers are once again turning to trompe l'oeil for small spaces. Artist Richard Haas of New York has been hired by architects and designers all over the country to paint images of fine niches and cornices on the walls of buildings otherwise devoid of character. Locally, a windowless building wall near 7th Street and Market Space NW is enhanced with a colorful trompe l'oeil mural.

There is a similar revival of marbling and graining, for much the same reasons Colonial and Victorian Americans turned to these techniques -- it costs less than the real thing.

Designer Antony Childs, for example, created an unusual and exciting ambience in one Georgetown dining room with a floor that appears to be inlaid marble and porphyry, a dark red speckled stone. Actually, it was painted by New York artists Luis Molina.

"I wanted the dining room to be a romantic and unexpected space -- particularly in predictable Georgetown," said Childs. The effect is at once dramatic and startling. But as Childs points out, the strong floor pattern can only be tolerated for a few hours -- such a solution would not do for a living room. Because dining rooms are used for only a few hours at a time, he felt free to be flamboyant in the decor despite the room's small size. To absorb sound reverberating from the hard floor, Childs had the walls upholstered.

Angus and Joanne MacBeth's dining room displays an even less orthodox approach to illusion. In a plan executed by Weibenson & Associates, the wall between the dining room and the kitchen is pierced several times. The central hole was to have been a complete arch; however, the presence of pipes in the wall precluded opening the wall more than half an arch.The solution was to frame the opening and the entire wall in painted classical arches and columns. The result is more than a supergraphic, but less than pure trompe l'oeil.

Architect Bill Morrison, meanwhile, decided not to touch a second story porch, complete with columns, balustrade, wooden shutters and siding, when he added on a two story entryway that enclosed the porch and made it part of the interior. The home of Rep. Stewart McKinney (R-Conn.) originally had a second story side porch opening onto a narrow side yard. Morrison's two-story atrium now encloses it. Rather than confine the second story hallway with a traditional wall, Morrison, by leaving the old porch, preserved the illusion of "setting out" in a climate-controlled open hallway that allows light into the windows of the bedroom that opens onto the porch. The illusion of the old side porch is retained and in its new context the porch serves as a vehicle for bringing light from the skylight in the entryway into the second floor. Mirror, Mirror, On The Garage Wall

Washington architect Pamela Heyne is fascinated with the use of mirrors in residential settings. Author of a book to be published next fall by Van Nostrand Reinhold, Today's Architectural Mirror, Heyne offers two unusual ideas for expanding spaces with reflective glass.

In the illustration above, a periscope is created for a basement apartment with mirrors. Using mirror-like reflective glass, a view is transmitted from the outside to a lower mirror, bringing more light into a subterranean room. Heyne claims the periscope can be set up for almost any room that is partially below grade. Both mirrors must be parallel at 45 degrees.

In the top illustration, reflective glass is installed in the back of a garage at the end of a small garden. The back of the house and the full yard is reflected in the glass, creating the illusion of a larger yard.