"Mrs. James Smith and Grandson," an 18th-century portrait by Charles Willson Peale, has been acquired by the Smithsonian Institution's National Museum of American Art.

If offered by a dealer, a Peale of such quality might today bring as much as $500,000. This one was acquired from the family collection of Wilson Levering Smith, a descendant of the sitters. It came to the museum partly through purchase, partly through gift.

The precocious boy portrayed, though only 8 years old, is polishing his oratory by bending his attention to Hamlet's soliloquy. Peale, who began the work in September 1776, was used to gifted children. He had many of his own, 17 in fact, five of whom -- Raphaelle (1774-1825), Rembrandt (1778-1860), Rubens (1784-1865), Franklin (1795-1870) and Titian (1799-1885) -- lived up to their given names by becoming painters, too.

Their father, the son of a schoolmaster, was born in Queen Annes County, Md., on the Eastern Shore in 1741. At 12 he was apprenticed to a saddler in Annapolis, and soon became adept at a variety of skills. He painted signs, worked silver, made clocks and false teeth (including, so it's said, a set for George Washington). Though a largely self-taught painter, he did study briefly with John Hesselius, in Philadelphia, and John Singleton Copley, in Boston, before journeying to London in 1766 where he worked with Benjamin West, that benevolent befriender of young colonial painters. Peale came home three years later, and settled in Philadelphia in 1776. Always interested in science, he opened a museum of art and natural history adjacent to his studio.

The quality of Peale's art is a bit uneven. "His portraits," observes Joshua C. Taylor, the museum's director, "are often a little bit remote. But this one has an extraordinary humanity. The child, obviously, feels totally protected. Though I don't go overboard for this sort of picture, this one is a gem." Though the museum own miniatures by the artist's brother James, by his sons Raphaelle and Rembrandt, and his granddaughter Mary Jane, "Mrs. James Smith and Grandson" is the first Charles Willson Peale to enter its collection. The 3-foot-high portrait is in fine condition. It will go on view on Tuesday in the museum's Lincoln Gallery. The National Museum of American Art, formerly the National Collection of Fine Art, is at Eighth and G streets NW.