MONOCLES are the order of the day in the "Portraits from the American Academy and Institute of Arts and Letters" at the National Portrait Gallery. So are mustaches, fur-collared overcoats and walking sticks.

The 24 paintings, drawings and sculpture come from the Academy and Institute, founded at the turn of the century by a group of writers, artists, architects and composers. The portraits depict venerable members from the early years.

It was then a stuffy organization that wished to emulate the long-established European academies in promoting culture -- a very conservative, highbrow and self-important notion of it at that. For example, there were attempts -- unsuccessful -- to blackball Carl Sandburg and such "undistinguished" and "radical" poets as T.S. Eliot and Archibald MacLeish.

The portraits here were collected between 1915 and 1940, a time when clarion calls went out to the membership to contribute such things. An assortment of varying quality came in.

Mark Twain was one of the first seven members (1898), and he's shortchanged in his portrait. It's an oil sketch done as a magazine illustration, greenish-black like a faded photograph. The artist, Abbott Handerson Thayer, was so in awe of the author that he painted him looking off, remote; hardly the lively wag we know and love.

Artist Elihu Vedder looks more like Twain, with his generous white mustache. And it's entirely possible one could have gotten the humorist to dress in kimono and velvet skullcap as Vedder did when he sat for William McGregor Paxton. (Vedders' work can be found in the ethereal women and imaginative scenes in murals at the Library of Congress and illustrations for "The Rubaiyat of Omar Khayyam.")

Booth Tarkington didn't fare well either, and neither did his dog. Here is the author, an imposing full figure, with fur-collared overcoat and cane. Beside him sits the black poodle "Wops," which Wayman Adams made practically invisible. Tarkington, who wrote the "Penrod" novels of boyhood, as well as "The Magnificent Ambersons," appears supercilious and phlegmatic. And why, for heaven's sake, is he wearing that coat indoors?

The Academy was the elite, 50 members originally drawn from the Institute, which numbered 250 members (the two groups merged in 1976 to become the Academy-Institute). A frail, aged Julia Ward Howe, poet and composer of "The Battle Hymn of the Republic," was the first female member of the Institute (1907) and of the Academy (1908) -- but not until she was 89 and an institution herself. She was the only woman to be elected until 1926.

Howe is feeble looking and faint in comparision to Childe Harold's Impressionist self-portrait -- beautifully shimmery, with rainbow colors streaming down his white shirt, aqua eyes that sparkle in his pink face. Even he looks a little stiff.

But posing itself can be imposing. In an autobiographical novel, Carl Van Vechten recalled sitting for his portrait by Martha Susan Baker: "I climbed to the model-chair, seated myself, grasped the green book that was part of the composition, and automatically assumed that woe-begone expression that is worn by all amateurs who pose for their portrait."

Actually, he looks like a young man who takes himself far too seriously.

PORTRAITS FROM THE AMERICAN ACADEMY & INSTITUTE OF ARTS AND LETTERS -- Through September 20 at the National Portrait Gallery.