AN art gallery that sounds like a law firm --

Taggart, Jorgensen & Putman--opens today in Georgetown. The 6-year-old firm hails from Los Angeles, where it has specialized in American art from the 19th and early 20th centuries. The handsomely-renovated, two-story space at 3421 P St. NW is just a few doors from another purveyor of vintage American art, Adams Davidson Gallery--a convenience for browsers and collectors.

The inaugural show of 70 paintings suggests that the American specialty will prevail here as well. Taggart, Jorgensen & Putman have gathered an impressive array of names, given the shortage of good material in this field. Severin Roesen (an elaborate still-life with fruit), John F. Peto (two small paintings with pipe and books), Childe Hassam (an Italian landscape) and Edward Potthast (a small "Purple Beach Scene") are all represented in more than acceptable examples.

There are also intriguing works by names long forgotten, such as John O'Brien Inman, whose charming genre painting from 1861 shows an entrepreneurial New York street urchin selling fruit and Civil War maps along with shoeshines. Impressionist Daniel Garber, from New Hope, Pa., is represented by a beautifully modulated 1910 study of his wife sewing by a window. Among some curiosities is a garishly colored view of the Potomac by John Ross Key, Washington painter and grandson of Francis Scott Key. The painter died in 1920.

The earliest work in the show is an 1846 portrait of the Hudson River paddle steamer "Perry" by John V. Cornell (clearly made under the influence of the better-known James Bard). The most recent work consists of two large oils from the 1930s by Norman Rockwell, one obviously made as an ad, and showing a weathered fisherman with lures in his hat and a can of Ballantine Ale in his hand, priced at $30,000.

The gallery has a sub-speciality in turn-of-the-century European art--a new but welcome and growing market in Washington. Among several pleasing Victorian watercolors and sometimes too-too sentimental paintings of kids with dogs is a fresh little jewel of a watercolor by Scottish Art Nouveau illustrator Annie French, titled "The Pious Maid." Though few Americans will have heard of her, the naive quality of the drawing and the wonderful patternings are utterly winning.

Paintings in this show are priced starting at $2,000 and go up steeply to $35,000 for the 1871 Severin Roesen "Two Tiers of Fruit" and then to $110,000 for a Childe Hassam "View of Posilippo, Italy." At least one viewer would be just as happy with the French, which costs $2,500.

The gallery has a less promising inventory of contemporary paintings that look like old ones but aren't. About them, the less said the better. The current show continues through July 9, and will be open 10:30 to 5, Mondays through Saturdays. American Art at the Hull

American art from the first half of the 20th century is the subject of the current show at Hull Gallery, 3301 New Mexico Ave. NW. Each year, proprietor Ann Hull travels widely to gather affordable art--mostly small-scale works on paper--for beginning collectors. This year's harvest is the best yet, with especially strong watercolors and drawings by Milton Avery, Oscar Bluemner, Charles Demuth, George Luks, Jerome Myers, John Sloan and Max Weber--to mention only a few.

The title--"Trends in American Painting, 1900-1950"--is a bit overblown, but it does describe an attempt to touch upon major trends (if not always in major examples) such as modernism, synchronism, regionalism, precisionism and abstraction. More important, perhaps, is a chance to glimpse well-known artists in rare and intimate moments: Thomas Hart Benton in his synchronist phase, for example, or William Glackens summing up the swift pace of a Mary Poppins-like "Girl In Yellow Hat."

The biggest surprise, however, comes in three drawings of great charm and versatility by Arshile Gorky, including the deliciously painted tipsy pink still-life, titled "Flowers In A Vase," the witty "Studies of Two Men," and the very tender "Family Dream Figures." The show, which also includes prints, continues through June, Tuesdays through Saturdays, 10 to 5.