It is not even 1980, but the fin de siecle seems already upon us.

Modern abstraction in art has long ago reached its dead end. The latest fashion in architecture shows an effete sophistication, a tired delight in playful reveries, that seem as decadent as the languid art nouveau at the end of the last century.

This absent-minded doodling of disparate architectural elements, assembled not so much into architecture as into three-dimensional collages, calls itself "Post-Modernism."

It seemed harmless enough, yielding mostly words and drawings, but few buildings. So far Post-Modernism is safely confined between the covers of arty New York magazines.

But now, it seems, the fad has arrived in Washington, which may mean it has arrived. We are to see a clever little touch of it on the building of the Phillips Collection, of all places.

The Phillips, most art lovers will agree, is one of the finest private galleries anywhere. It is not just "Washington's best alternative to the National Gallery," as someone has called it. It is also proof, in a city where such proof is sorely needed, that a splendid institution need not appear institutional.

There is, if I am correctly informed, no cause for alarm. The Phillips, located at 1600 21st St. NW, is not to be enlarged and the construction work for which architect Arthur Cotton Moore has been engaged is not intended to change the gallery's uniquely intimate and pleasantly ramble-scramble character.

That is why Arthur Cotton Moore's caprice, while satisfying gallery director Laughlin Phillips' urge to build, will not hurt. It will simply be more ramble-scramble, mostly hidden in the dense foliage of the old trees on 21st Street.

What the caprice is supposed to help is the safety of the magnificent Phillips collection, the oldest collection of modern art in the United States. A vast number of paintings are now stored in the basement and stashed away in closets and bathrooms without adequate fire protection and, humidity control. The Phillips simply needs more room for storage. It could also use a little more space for offices and a library.

Moore's will be the fifth addition to the residence of Major Duncan Clinch Phillips and his wife Eliza Laughlin, built in 1897. It was designed by Hornblower & Marshall, the capital's most fashionable architects at the time, who selected a chaste Georgian Revival style for the job. They did more exuberant work eleswhere.

The first addition, a T-shaped, one-story wing was added in 1907 by the same architects. It now serves as the music room where the wonderful Sunday concerts are held. In 1920, when the private collection was opened to the public, McKim, Mead & White added a second story over this wing to serve as gallery space. Three years later a fourth floor with a mansard roof was added, totally chainging the original appearance of the house. By 1930, the next generation, Majorie and Duncan Phillips, turned over the entire house to gallery use.

A completely new building, free-standing, but connected to the old agglomeration with an ugly steel and glass bridge across the alley, was designed by George Rowe and built in 1959. It ranks among this city's least distinguished works of modern architecture.

Moore has only a few feet north of this limestone box to add on to. He has chosen to fill this space with what would have been utterly unthinkable only a few years ago - a replica of the original south corner of the complex, a job of post-modernistically Georgian Revival, red brick, Flemish bond, Mansard roof, shutters and all.

"It sort of put the whole thing between bookends," Moore told me.


To show up this bit of architectural flimflam, Moore joins it to the Howe building with mirrors, as it were. There is first, on the street level, a hugh tinted glass panel which serves as sliding door for the driveway for trucks.

The glass panel is surmounted by a glass cylinder, jutting out. That, in turn, is surmounted by a glass cyclinder, jutting in. The mediocrity of the limestone box with its bronze Braque bird over the entrance door is further - jazzed up, shall we say? He adds two stories, one faced with brick and the other with glass.

It is wild. It is amusing. It is Post-Modern.

And it is probably harmless.

At least as long as the trees stay alive. CAPTION: Illustration, Architect's view shows original Phillips house, left; the 1959 Howe building, right center; and planned "Post-Modern" addition, right.