David Gilmour Blythe of Pittsburgh painted truly nasty pictures. He was born in 1815 and died -- of "delirium from drink" -- in 1865. There is no one else quite like him in he history of American art.

"The World of David Gilmour Blythe," an exhibit of his paintings, sculptures and drawings, goes on view today at the National Museum of American Art -- which used to be called the National Collection of Fine Arts, but changed its name this week.

It is not a pretty show.

Other painters of the age filled their art with lofty things. The world that Blythe protrayed is a place beyond redemption. Its inhabitants wear rags, its horses are but bags of bones; the air is full of soot and justice is a joke.Blythe's propectors explore a new world whose fertile earth has already turned into poisoned, stinking mud.

He often protrayed children, but not those of Currier and Ives lithographs. Blythe's urchins are dough-faced semi-idiots. They misbehave, they steal, they smoke thick cigars. Dickens saw his street waifs as victims of society, but Blythe's were born corrupt. His "Oatmeal Eater" (1856-58) is a moon-faced, dull-eyed moron who is dribbling his porridge and scratching at his lice. Though at first glimpse he resembles the better sort of vagabond -- say, Tom Sawyer or Huck Finn or the Dead End Kids of Hollywood -- there is nothing cute about him. Unlike those charming rascals, he is not saved by spunk.

Blythe was just as hard on most adults, although he rather liked Abe Lincoln. The black man who is the subject of "Ole Cezar" looks as if he's just climbed out of his tomb. Blythe's portrait of Joe Cowell shows a beat-up Irishman whose face is red with drink.

While other skillful satirists of the 19th century -- Nash or Twain, for instance -- attacked the bad to boost the good, Blythe had no such motives. Bruce W. Chambers, the University of Iowa scholar who organized this show, writes that the painter, in his few surviving letters, reveals "an astonishingly comprehensive antipathy to the Irish, Germans, Negroes, press, pulpit, courts, juries, judges, lawyers, politicians, poets, and rotgut whisky."

Blythe's earliest portraits, although touched with acid, look much like those produced by other itinerant limmers of his time. Though his brushwork improved later, his art was always crude. "Nobody argues that this guy is a great painter," says Chambers, "but he has one of the most interesting careers in 19th century art."

Chambers, in his thoughtful catalog, suggests some explanations for the sour wit, the virulent vulgarity in which Blythe drenched his paintings.

The artist's father, a Scottish immigrant and a strict Presbyterian, surely taught his sons that man was born in sin. Blythe's beloved wife -- he left his church to marry her; she was a strict Catholic -- died suddenly, probably of typhoid, in 1849. And then things got worse. Blythe's most ambitious project, his "Great Moving Panorama of the Allegheny Mountains" (he claimed in his ads that it was a mile long), was confiscated for unpaid freight charges in 1852. His father died that year as well -- adding to Blythe's guilt.

Blythe thought himself a learned man. He studied the Old Masters, and his copy of "Peasants Drinking and Smoking," a 17th-century Dutch genre scene by David Teniers the Younger, is included in this show.

Also he wrote poetry: . . . I have grown Almost gray and half-demented In trying to find some place where. . . Mand and man might "dwell Together in unity," and not tell Lies on one another. . .

The railroads had not yet brought prosperity to Blythe's Pittsburgh. The city was, in his day, an industrial sinkhole torn by crime waves, choked with soot and flooded with unemployed immigrants. Blythe's "Prospecting," a painting of the nearby oil fields (the prospector is standing knee-deep in oily muck), may be the first picture of pollution painted in this country.

The conquering of the new world, the mining of its riches, the labors of the working man -- like the purity of childhood -- had no appeal for Blythe. "In a rather remarkable way," writes Joshua C. Taylor, the museum's director, "he combined the inner assurance of a confirmed mystic with a pragmatic disillusioned vision. . . . Unlike a true religious zealot, he seems never to have glimpsed the glory of salvation, but found himself inextricably mired in a paradise already lost." The show closes Jan. 11.