When Charles Willson Peale was in his mid-80s, he travele from Philadelphia to New York to propose marriage to what would have been his fourth wife, because he wanted someone to take care of him for the last quarter century of his life. No, there's nothing wrong with that last sentence. He thought he would live to be 112.

He probably thought that since he had accomplished enough for several lifetimes he would be permitted to live them.

Born 250 years ago tomorrow in Queen Anne's County on the Eastern Shore, and currently the subject of celebrations in Baltimore, Washington and Philadelphia, Peale was one of the most astounding phenomena in the history of American art.

He painted portraits, landscapes, still lifes, history paintings. He initiated the portrait which contained more than one person in America and painted more life portraits of Washington (seven) than any other artist. He engraved and sculpted. He opened and ran the first real museum in America. He was an inventor. He exhumed the bones of a prehistoric animal that had significant scientific implications. And he founded a dynasty of artists that lasted for several generations.

In fact, says Peale scholar Lillian Miller, it was precisely the fact that Peale did so many things that eclipsed his reputation for more than a century after he died. "He was such a varied individual that he was dismissed as a jack-of-all-trades. He had a pleasant personality and it was mostly his personality that was discussed by historians rather than his paintings. When they were discussed at all, it was his Washington sittings. But he was overshadowed by [John Singleton] Copley and [Gilbert] Stuart, who were considered more sophisticated by historians and critics."

Since World War II, however, and particularly in the last 25 years, Peale's portraits have been increasingly shown and he has been increasingly studied, as Ms. Miller's current schedule shows. The editor of the Peale Family Papers at the National Portrait Gallery in Washington, she participated yesterday in a conference at the portrait gallery on Peale and other American "Old Masters," including Benjamin West, Copley, Stuart and John Trumbull. Tomorrow, she will be speaking in Philadelphia; and today she will speak at Baltimore's Peale Museum, which is having an afternoon celebration of the birthday.

The subject of all these tributes did not have a particularly promising beginning, Ms. Miller said in a telephone interview last week. Born of a father who had been exiled from England for embezzlement, he grew up in Chestertown, where his father taught school, and was apprenticed to a saddler.

"He bought himself out of the apprenticeship because he felt it was a very servile position and very much resented the dominance of his master." Seeing portraits on a trip to Norfolk, Va., "he said to himself, 'I could do better than that,' and subsequently in Philadelphia he bought a book on how to paint and some materials."

Not long after, he fled to Boston to avoid debtor's prison, and there he saw copies of old masters by John Smibert. "They were very important influences on many artists," Ms. Miller said. Moreover, he saw Copley paint. Before that, "painting was something to add to other craft jobs to earn a living. Watching Copley atwork, he became much more involved in the idea of the artist as a professional. And Copley was painting the aristocracy of Boston, which impressed him."

Back in Maryland, his debts paid off out of his wife's inheritance, he impressed his patron John Beale Bordley, who raised a purse to send him to London to study with Benjamin West. There for 2 1/2 years, "he learned everything there was to be learned about art at the time, and came back a trained and professional artist."

Moving to Philadelphia just before the American Revolution, he served during the war. "He went to Valley Forge with Washington. He took along his miniature kit, and painted miniatures of many officers involved in the Revolution. Some are the only images we have of the people," said Ms. Miller, who pointed out what many do not know: with Copley, Stuart and Trumbull all out of the country, Peale "was the only major painter working in this country during the Revolution."

In 1779, he painted a full-length portrait of Washington at the battle of Princeton. "It was copied by many artists and engravers," and was, Miller said, the best-known image of Washington until a Stuart portrait took its place about 15 years later.

"Peale painted more life portraits of Washington than any other artist: in 1772, when Washington was a colonel in the British army; in 1776, 1777, 1779, 1783, 1787, when Washington was sitting at the Constitutional Convention; and 1795, when he painted Washington as President."

By that time he had opened his museum in Philadelphia, in which he combined portraits with natural history items such as minerals, animals and birds. "It was the first continuous permanent institution of its kind in this country," Ms. Miller noted, "and it became the most important natural history and art museum of its time. It was the model for other museums established in New York and Boston."

With his interest in natural history, Peale was naturally excited by the discovery of evidence of a large prehistoric animal at Newburgh, N.Y. He went there and in 1800 unearthed enough bones to form two skeletons of a large prehistoric animal which was named a mammoth or mastodon.

The mastodon provided significant evidence that large forms of life lived in this continent. The discovery of the remains of such large animals that had become extinct, Ms. Miller said, also challenged the "great chain of being" theory of creation and "gave rise to the new scientific theory of evolutionary change."

As "a kind of inventor," Miller said, Peale "adapted inventions and made them work. One of his most important developments was the polygraph, a writing machine with two pens that made duplicate copies of letters. [Thomas] Jefferson ordered an early one, and made suggestions to Peale for improvements." One of these instruments that Peale made is at Monticello.

Although in later years his children took over much of the painting, Peale continued to paint almost until his death. "He thought his painting had improved with old age," Ms. Miller said, and she agrees that "some of his most beautiful paintings" are from the period after he was 60. He painted "a beautiful portrait of his wife in 1805." In the same year he took up again and finished a family portrait begun in 1772 which "has become an American icon."

In 1808, he painted a depiction of the exhumation of the mastodon, "his first history painting." It is at Baltimore's Peale Museum. And in 1822, when he was over 80, he painted the full-length portrait of himself lifting the curtain to his museum which is surely the best-known image of Peale himself.

By that time, Peale's son Rembrandt had opened a Peale Museum in Baltimore (in 1814) and was also a famous portrait painter. Peale had a penchant for naming his sons after great painters, and three of them became notable painters themselves: Rembrandt, a portraitist; Raphaelle, whom Ms. Miller calls "a very important still life painter"; and Titian Ramsay, "recognized as an important naturalist artist." Moreover, Peale taught his brother James to paint, and James had three daughters who became artists. One of them, Sarah Miriam Peale, Ms. Miller says, "was the first woman painter in this country who had a long, continuous professional career." The dynasty did not stop there, however: It went on down to the third and fourth generations.

Of Peale himself, Ms. Miller thinks he ranks with the finest American portraitists of his age: Copley, Stuart, West, Trumbull. "He painted some very fine paintings, and they are highly naturalistic so that the images are probably as close as we can come to how these people actually looked. He was the first American painter to paint the 'conversation piece,' the portrait with more than one person in it. When Copley heard that Peale was painting portraits with two or more people in them he felt the necessity himself to do that kind of thing. Peale also did full-length allegorical portraits with all sorts of symbolism in them, and portraits of children in an outdoor setting."

Peale, by the way, did not succeed in his mission to New York to get a fourth wife. Instead, Ms. Miller notes, on the return trip "when he reached the Philadelphia wharf it was storming and there were no porters available to help with his trunk. So he carried the trunk up the hill himself. It strained his heart and he died within the year," on Feb. 22, 1827.

Peale paintings in Baltimore

The Peale Museum has four Charles Willson Peale paintings (( including "Exhuming the First American Mastodon" (1808) and "Mr. and Mrs. James Gittings and Granddaughter" (1791). All four are on view.

At the Baltimore Museum of Art are eight paintings, six on view including portrait pairs of Mr. and Mrs. Richard Gittings (1788) and Mr. and Mrs. Thomas Ringgold (early 1770s).

At the Maryland Historical Society are 28 Peales, 10 miniatures, 17 portraits and the group portrait and scene "Washington and His Generals at Yorktown" (about 1781). This and 10 others are on view, including "Mrs. Richard Tilghman and Sons" (1789) and "Thomas Stone" (1774).

Peale's 250th

What: A day of conversation and music in commemoration of Charles Willson Peale's 250th birthday.

Where: The Peale Museum, 225 Holliday St.

When: 12:30 p.m. to 1:30 p.m., chamber music by Musica Antiqua, including compositions by Rembrandt Peale. 2 p.m., Lillian Miller, editor of the Peale Family Papers at the National Portrait Gallery, Washington, will speak on "Charles Willson Peale: A View from the 20th Century."

Call: 396-1149.