The high point of Charles Willson Peale's career as a museum director came in 1801 when two nearly complete skeletons of a mastodon were excavated from a bog in upstate New York. Besides mounting one skeleton in his Philadelphia museum, Peale recorded the momentous event on canvas.

"The Exhumation of the Mastodon" contains 75 figures (friends, family, most of his 17 children and two wives) arranged Greek- frieze-style, with the artist overseeing the digging, a bone drawing in one hand. Self- important, to be sure, but the man was a character.

Peale's reputation as an 18th-century Renaissance man -- inventor, natural scientist, patriot and one of a family of artists -- neglects his skill as a serious painter. The last time his works were given a solo show was at a Philadelphia auction in 1854. The National Portrait Gallery makes amends with a major exhibition opening Friday.

"Charles Willson Peale and His World" is a comprehensive survey of a prolific, multifaceted life. The Maryland native invented a steambath, a wooden arch bridge and new methods of taxidermy; founded the world's first popular museum of natural science and art; and chronicled the country's early statesmen. Peale feared that critics would fault him for his liberal-arts approach, but there is unity in his body of works.

Five of the seven life portraits he made of George Washington, ages 40 to 67, are on view, along with precise portaits of early American political and military figures. A number of life-size portraits of Maryland's and Philadelphia's gentry from the late 1700s show family members in candid poses. The "Peale face" recurs: optimistic ovals, with cheerful expressions preserved for posterity.

His motto was "art and nature." The public gawked at Peale's natural-history specimens in a skylighted wing of his house, opened as a museum in 1786. Minerals, bones, Indian objects, stuffed birds, shells and fossils were displayed beside his own portrait gallery. (Later it moved to free space upstairs at Independence Hall.) The collection is recreated here, starting with the autobiographical portrait from 1822, "The Artist in His Museum," in which Peale is shown drawing aside a curtain to reveal the museum's Long Room.

When Washington visited Peale's museum in 1797, he reportedly bowed politely to the painted figures in "The Staircase Group," acknowledging later that he thought they were flesh and blood. Peale's life-size "deception," an experiment with light and perspective, was aided by a real step descending from the canvas to the museum floor. The trick still works.

CHARLES WILLSON PEALE AND HIS WORLD -- Opening Friday, continuing through January 2 at the National Portrait Gallery.