WHEN Baltimore collector Dr. Claribel Cone died in 1929, she left paintings by Matisse, Pablo Picasso, Cezanne, Gauguin, Degas and Renoir to her sister, Miss Etta Cone, with the following stipulation: The collection should ultimately go to the then-new Baltimore Museum of Art "if the spirit of appreciation of modern art in Baltimore becomes improved." It's too bad that Claribel Cone wasn't around last week to see how much modern art was being appreciated in Baltimore. She would have witnessed:

The inauguration last night of the Alan and Janet Wurtzburger Sculpture Garden at the Baltimore Museum of Art, where 24 sculptures by Henry Moore, Calder, Noguchi, Lachaise, Maillol and other 20th-Century masters go on view to the public today.

The publication of "Baltimore's Public Art," which catalogues the 84 sculptures erected all over the city since 1965, when the "1 percent for art" ordinance -- one of the most active in the nation -- went into effect. Monumental works by Kenneth Snelson, Mark di Suvero, George Sugarman, Barbara Hepworth and Henry Moore have arisen, with more on the way, including a $250,000 Rauschenberg mural slated for the Equitable lobby.

The celebration marking the opening of "Sculpture 1980," a huge survey of contempary work from all over the country, now on view in a handsomely renovated old shoe factory, the largest of several reconverted structures (including a former B & O Railroad Station, an auto body shop and a tire outlet) that now constitute the Maryland Institute, College of Art, the nation's oldest accredited art school, and currently one of the best.

After an opening dinner at the school's elegant main building Tuesday night honoring the city's staunchest art supporter, Mayor William Donald Schaefer -- as well as corporate donors who coughed up $20,000 to back the "Sculpture 1980" show -- hundreds of artists, collectors and just plain Blatimoreans made their way through the exhibition, and then proceeded to the city's revitalized Inner Harbor area to watch some nontraditional sculpture events take place.

Avant-gardist Charlotte Moorman, who was scheduled to have been hoisted aloft by 20 helium baloons -- playing a cello as she rose -- was delayed by bad weather and didn't show. (Instead, a violent storm picked up a geodesic dome and hoisted it aloft.) Undeterred, visitors strolled among a dozen site-sculptures and other works made from neon, sound, wind, wood and tobacco gauze. One triumphant artist shouted, "It floats!" as he launched his work on the water. Across the harbor, three stainless steel cubes seemed to be tumbling down historic Federal Hill -- a sculpture by Carolee Thea of New York, another manifestation of "Sculpture 1980."

The Tuesday-night revels were the climax of two days of workshops and other sculptural events organized by several Baltimore artists and institutions to coincide with the 11th International Sculpture Conference which closed in Washington yesterday. "We wanted people to come and see what a cultural renaissance we've had in Baltimore, and what it has meant to our artists," said Mary Ann Mears, a young sculptor and arts activist whose swirling red aluminum sculpture "Red Buoyant" stands before the IBM building on Pratt Street. "The title describes how I feel about this city," said Mears.

Mears is not alone.Her enthusiasm for the Baltimore art scene is shared by many artists, citizens, businessmen, corporations and, most importantly, the city government of Mayor Schaeffer -- all of whom seem to work in a symbiosis that should be the envy of any city in America.

The creation of "Sculpture 1980" is a good example of how well that relationship works. Professor Fred Stern, of the University of Maryland, Baltimore, had the idea of tying into the Washington sculpture event, and it caught fire immediately. Artists and art institutions took the initiative and, with volunteer help, did all the work.

Of the $25,000 needed, $5,000 was obtained from the National Endowment for the Arts and the Maryland Arts Council. The rest was quickly raised from 20 corporate sponsors, among them Baltimore Gas & Electric, the C & P Telephone Co., T. Rowe Price Associates, and the Rouse Co., which is currently involved in building Harborplace on the Inner Harbor, a complex of restaurants and shops due to open early in July.

"We felt this was a unique opportunity to showcase new talent from all over the country during the Sculpture Conference," says Robin Coplan, exhibition director for the Maryland Institute, College of Art and chief organizer of "Sculpture 1980." "People kept saying it couldn't be done, but we did it."

The organizers asked 40 internationally recognized sculptors starring in the Washington sculpture conference to suggest other artists they found exciting. "The response was tremendous," says Fred Lazarus, the Maryland Institute's new president. As a result, 56 sculptors from 17 states and Canada were recommended and invited to participate. In addition, Maryland sculptors were invited to submit work to a jury composed of three Institute facutly members. Twenty-nine were selected and included in the show, which in its final version also included several artists from Washington, among them Nade Haley, Jim Sanborn, Elizabeth Falk, John McCarty, Martha Jackson Jarvis and Nizette Brennan.

"You wouldn't get this diversity if the show had been selected by one curator instead of by the artists themselves," said Coplan. It's true. Starting with a huge, mural-like relief made of corrugated cardboard by Reeva Potoff of New York, the show in the shoe factory plunges boldly into every aspect of current three-dimensional expression, presenting a new talent-survey of grand dimensions. There are a few clinkers, but far fewer than the average share -- something of a miracle, considering the unusual and cumbersome formula that underlies the selection.

Moving from room to room (this space was designed for classrooms and studios, not exhibitions) one finds a small surprise behind every door. The show starts with a chuckle in a room occupied by 11 nearly life-size lady Marines, all made of fired clay and all unarmed, though little toy soldiers do battle on their laps. "The B.A.M.S.," as they are called, are the work of Marilyn Lysohir of Pullman, Wash. Dan Sellers of Baltimore takes figurative sculpture considerably closer to reality in a work entitled, "I'm Proud of My Father," which consists of a reclining chair and a real human being -- his father -- who actually sits in the chair during posted hours.

From a wide range of media, including an intriguing fiberglass portrait bust by Luis Jimenez Jr. of Texas, several strong works in wood stand out. Fine craftsmanship is a major element in a carved trompe l'oeil "Table Saw," made entirely of wood by Allan Adams of San Francisco; and in a large, obsessively detailed, take-apart piece with tiny sliding doors -- a tour-de-force of parquetry by Mitchell Braumbart of Baltimore.

New Yorker Mel Kendrick has made a striking work from cedar 4-x-4's, carved into curving shapes that argue convincingly against the wood they are made of. In one of the show's strongest works, Ursula Von Rydingsvard, also of New York, has made an environmental floor piece from a few hundred hacked but harmoniously pegged-together blocks of cedar that effectively conjure a western desert landscape.

There are several successful works with ritualistic overtones, notably one by Clyde Connell, a 79-year-old woman from Elm Grove, La., and another by Linda Fleming of Colorado, installed in the median strip in front of the shoe factory. Baltimore artists James Paulsen and Norman Carlberg also make a strong showing. There is much more -- all worth seeing before the show closes on June 26. Hours are Monday through Saturday 10 a.m. to 4 p.m., Sundays noon to 4 p.m. and Wednesday and Thursday evenings till 9.

By contrast, the new Wurtzburger Sculpture Garden at the Baltimore Museum seems tame, a small group of 24 20th-century classics nestled peacefully behind poured concrete garden walls and a handsome iron gate. Ten years in the planning, this 17,000-square-foot garden was designed to hold the personal collection of the late Alan and Janet Wurtzburger, whose family estate, Timberlane, was surrounded by tree-shaded lawns where works dating from Bourdelle and Rodin to David Smith and Anthony Caro were beautifully installed, each in its own special place among lush green plantings.

It was hoped that the museum's walled-in garden, with its graduated bluestone terraces and sylvan backdrop (the Johns Hopkins dell) could recapture the special quality of Timberlane. To date it has not, but as the birch, willow oaks and boxwood develop, the harshness of the perforated concrete walls will no doubt be tempered.

Meanwhile, the installation has some real probelms, one of the most obvious being the placement of a decorative piece by Somaini at the edge of the pool, like a vase of flowers waiting to be moved. The powerful Zadkine work, "May, 1940: The Destroyed City," a smaller version of the memorial to the destruction of Rotterdam in Holland, deserves far more respect than it gets here, juxtaposed with Calder's light-hearted stabile "Four Dishes." Nearby, other pieces by Lipchitz and Henri Laurens are clumped together in a disturbing overdose of angst. They need to be redistributed.

When the new wing (now a visible, fenced-in-hole in the ground) is completed, with its auditorium and adjoining cafe, the whole ensemble will no doubt come to life as a more satisfying whole. Till then, imagination will have to be pressed into service.

Meanwhile, inside the Baltimore Museum, the Cone Collection remains the great centerpiece. It was finally turned over in 1949 by Miss Etta Cone. The sisters would no doubt be happy and astonished to know that their city, at last, has caught up with them.