Although immortality cannot be found in a fountain, as Juan Ponce de Leon learned, that didn't stop dentist Henry Cogswell from trying, writes James M. Goode in Outdoor Sculpture of Washington.

Cogswell dontated drinking fountains in his own name to any city that would have one. Most have been torn down, but Washington's still stands at 7th and Pennsylvania NW. The Temperance Fountain, a bronze and granite mini-pagoda, circa 1880, is topped with a crane, symbolizing the purity of water versus liquor, a concept the vain dentist vainly promoted in Our Town. But at least the fountain's dry.

Elsewhere in Washington, running waterworks abound, as a walk down almost any main street will show. For instances:

The Butt-Millet Fountain on the Ellipse was sculpted by Daniel Chester French in memory of two lost on the Titanic: Major Archibald Wallingham Butt, military aide to presidents William Taft and Theodore Roosevelt, and Francis Millet, artist, journalist and Civil War drummer boy, who gave their life preservers to women as the unsinkable happened on April 14, 1912.

A decade later Joseph Darlington died and the Washington Bar Association erected a fountain in honor of him: a life-sized nude nymph and fawn on a pedestal in a shallow circular pool at Judiciary Park at 5th and D streets NW. When Darlington's Baptist fellows protested the nymph's nakedness, writes Goode, sculptor Carl Paul Hennewein claimed she was "direct from the hands of God instead of the dressmaker." ON THEIR ISLANDS

Lest we forget Sen. Frances Newlands (1878-1917), founder of Chevy Chase, the Congress had a memorial fountain erected in 1933. Newlands' large round pool, with high-spouting jet, sits in a small park in the middle of Chevy Chase Circle, ringed with dense traffic (turns on in early May). Air traffic's the trouble at Theodore Roosevelt Island, where two fountains (maybe on by May) commemorate the conservationist.

There are two fountains for French friend Lafayette at his park, while JFK has three at his Center for the Performing Arts. The latter are frequented by coin-tossing types who don't realize they are, like the oracles of yore, trying to appease the spring sprites with sacred offerings. Many Roman coins, pots and golden jugs were found in the ancient baths of Bath, England.

Ancient rites meet the Carl Saganization of the cosmic conscious at the Expanding Universe Fountain, a granite, glass and metal work by Marshall Fredericks in the State Department's south courtyard. Orbited by stars and planets, it symbolizes man's need to explore space. More abstract is the $550,000 Cubi XI, one of 28 pieces in a series by David Smith, which sits high and dry in its pit-pool at the Universal North Building, whose Connecticut Avenue foyer holds "Fountain" by Alexander Calder. WATER AS SCULPTURE & AS SCULPTOR

The Seven-Eighths Circle Fountain at Columbia, Maryland -- also known as the Completed Circle Waterfall -- is a modern work by Jimilu Mason of Alexandria. Mason received a HUD award for the five-foot- diameter stainless-steel piece.

"I'm trying to incorporate water as part of the sculptural form. In the past, the water played on the forms," she says. "My sculpture tries to control the movement of the water. But water does its own thing. It wants to come together . . . to flow when you want to force it apart."

Mason has a second fountain at the Irish Oratory in the Shrine of the Immaculate Conception. It is a travertine Madonna sitting on a representation of a basalt outcropping like those seen off Ireland's northern shore. "The water's very meditative," she says. "It feeds the spirit. Others urge playfulness. Others stimulate. Some confuse." WATER AS TERRORIST

The new fountain in the Pennsylvania Avenue Development Corporation's plaza is not easy to categorize: water terrorism, perhaps. "It's jarring," says Goode. "It's a waste. The Park Service always planted the area beautifully. There was open greenery to relieve the pavement. Now it's all stone."

Other tepid works include the National Museum of American History's people- spritzer, the National Association of Broadcasters' corporate headwaters, Alexandria City Hall's colonial basin and Metro's watering hole at Silver Spring.

More wet offerings: the single stream recently found under the floor at the Pension Building, the two monumental Rayburn House fountains, the one over the Senate Garage, the Supreme Court's judicial ones, the Constitution Gardens' spray array, the Federal Reserve fount at 20th and Constitution, the fountain behind bars at the White House, the Federal National Mortgage Association fountain and water dribbles down 20-lb. test nylon line at the First American Bank, 1701 Pennsylvania Avenue. WHEN THE WATER RUNS DRY

And dry offerings: On Edgevale, a quiet street near Rock Creek, four old lions hold a bowl of four cupids who hold a bowl of four cupids who hold a bowl of ivy. At Walter Reed's Annex in Glen Forest is the Sea Horse Fountain, circa 1850, which had three basins, but lost the top tier when they took it apart for repairs in the 1950s.

A second fountain at Walter Reed is operational sometimes, but not often. The Penguin Fountain features a flock of four frigid birdies, all about 21/2 feet tall, perched on concrete blocks and protected by cobras. These waterfowl were sculpted to make military surgeon John Van Hoff memorable.

Immortality. "What fools these mortals be," burbles that Elizabethan cut-up Puck from his fountain at the Folger Shakespeare Library. The jaded sprite of "A Midsummer Night's Dream," by Barbara Putnam (1932) shrugs marble shoulders as he reflects on our foibles in the library's pool.

On midsummer eves before the magic of air-conditioning, Washingtonians sought respite from the heat beside the Bartholdi Fountain, drawn like moths to its electric lights, so rare in 1876. Its bronze serpents and caryatids were sculpted by Frederic Auguste Bartholdi, creator of the Statue of Liberty, for the Philadelphia Centennial. The Feds bought it for the Botanic Gardens for $6,000. It was stored for five years while the Gardens relocated, then moved to First and Independence SW.

Perhaps the most lavish of Washington's waterworks are the cascades of Meridian Hill, 13 liquid terraces walled in a 12-acre Italian Renaissance garden. An urban waterfall cascades from the summit of 16th Street to a pool guarded by grimacing dolphins. Beneath them, eight high geysers leap against a changing cityscape, splashing into a second, wider pool (turns on in May).

For the adventurous, the Columbus Fountain -- 15 feet of chiseled features -- presides at Union Station. A winged figurehead named "Discovery" rides the prow of his marble ship, sculpted by Lorado Z. Taft in 1912. The 45-foot beachhead also bears Isabella and Ferdinand, an American Indian who symbolizes the New World, an old man who represents Europe. A globe tops it off.

Across town, Dumbarton Oaks hosts the Pebble Garden Pool which is paved in Mexican stones with a wheat-sheaf mosaic. It holds a neoclassical fountain structure of seahorses with cherubic riders, a replica from Versailles. (Turned on 2-5 p.m. daily.) AT NEPTUNE'S OWN

Neapolitan penny-pitchers might prefer the granite grotto in front of the Library of Congress. There a sea god reigns over bronze tritons trumpeting their conchs and sea nymphs astride rearing mounts. This is the Court of Neptune Fountain, an excessively Victorian work completed by Roland Hinton Perry between 1897 and 1898. Its niches, filled with dolphins, turtles and sea serpents, and its classical theme indicate it might have been inspired by Rome's Trevi Fountain, sculpted by Nicolo Salvi in 1762. MUSES & MERMAIDS AMONG THE MISSING

Sadly, little remains of a second local fountain also styled after the Salvi work: The Friendship Fountain, commissioned in 1900 for John McLean at a cost of $200,000, once graced his fabulous Wisconsin Avenue estate. An entire school of artists spent more than 18 months completing the muses, cherubs, mermaids and wood nymphs that inhabited three tiers of wetlands. When the estate gardens were razed for wartime housing 40 years later, the fountain, cast at the Royal Foundry in Munich, was melted for scrap iron; the figures were stored and lost.

Recently, two mermaids and a wood nymph were found where they had been tossed, behind the McLean Gardens' old administration building. When the old housing was renovated as condomniums, the statues were cleaned and painted and now leer seductively in front of the sales office. The top piece of the Friendship Fountain, four cherubs bearing a brimming basin, now adorns the Gardens' main entrance.

Chubby cherubim are common fountain fare. Two make quiet music in the chilly beauty of the interior garden of the National Gallery's West Wing -- "Cherubs Playing With a Lyre" by Pierre Legros (1629-1714), sculpted for the Palace at Versailles and now part of the Andrew Mellon Collection. MELLON'S 'MERCURY'

Fountaineers owe much to Mellon. The central foyer of the West Wing, for instance, echoes with the gentle trickling of a 1937 acquisition: A wing-footed "Mercury," attributed to Dutch-Florentine artist Adriaen De Vries (1560-1627), is borne on the breath of a strong-winded sprite. Four dolphins bare their teeth and four gargoyles menace boys who dangle hands in the black marble basin.

Outside, on either side of the gallery's mall entrance, shining marble basins dump glistening sheets of water into rose-colored bowls. There it trembles at the brink, before rebirth as a quavering jet.

A 20-foot jet graces the Andrew W. Mellon Memorial Fountain at the Gallery's Pennsylvania Avenue entrance. Designed by Paul Manship, it is made of three tiers of bronze basins, the largest ever cast, from which cascades splash into a low granite pool. Beneath the basins are signs of the Zodiac, two feet wide and in high relief. They were designed by Sidney Waugh, says Goode, and each is sign is placed so that the fountain acts as an astrological calendar: Aries the Ram, for example, will be touched by the sun's rays on the vernal equinox, March 21, and will face the rising sun from then to April 20. Then comes Taurus' turn. THREE PLATES & A FOUNTAIN

But Pisces, rejoice! Water. Water's everywhere. The best yet roils beside skylight sculptures outside the National Gallery's East Wing. This is the only local fountain that may be viewed from above and below ground. The jets above foam down a chiseled stone wall to a glass-sided walkway at the Gallery's Cascade Cafe. Rivulets, salade nicoise and cold white wine.

Dining beside fountains can itself become a pursuit. Kiosk and tables are provided for patrons beside a lovely cascading waterfall at Pershing Park. The courtyard shared by the National Portrait Gallery and the National Museum of American Art offers the Patent Pending Cafe and two minimally exciting cast-iron fountains like rubber tires without rims. A.V.'s Ristorante Italiana has erected a funky rococo-Romanesque fountain, but left it out in the parking lot.

The Freer Gallery offers a peaceful pool for reflecting on the inscrutabilities of Orientalia. The Hirshhorn's circular fountain, intersected with ridges and ending in an asymmetrical hub like a misshapen bicycle wheel, reflects the symmetry of a sky framed by the museum's round courtyard.

"The water leaps up and down. It reaches almost to the top of the museum. And the whole space is taken up with the sound of it," says Steve Tatti, a former Hirshhorn employee turned freelance fountain restorer. "They don't turn it on that often, just for the openings. The energy costs to run it are $1,000 a day." THE LIONS' SLEEPY, SECRET WATERING SPOTS

There are more somnolent fountains: The intimate lion at "the Spanish Steps," long guardian of the walkway at S and 23rd streets, retains his royal mein. With deference, and towels, four Vietnamese children play beside him, wading in the shallow catch basin and stealing water from his lips.

Other members of his pride are en garde at 39th and Cathedral NW, Dumbarton Oaks and McLean Gardens.

Flora, instead of fauna? There's the Silver Spring, a huge acorn sculpture which marks the location of the spring, now dry, a half block off East-West Highway.

At Washington Catheral's Garth Fountain, 400 gallons of water per minute flow from the pistil of a 15-foot lotus sculpted by George Tsutakawa. The modernistic work clashes with the buttresses flying above, but provides a rhythmic burbling beneficial to meditation. There's a sculptured frog that tempts kids to wade.

Holy water runs deep in the sunken garden of the National Presbyterian Church at Nebraska and Van Ness NW. The fountain, on all day Sundays, is an enormous cross in a setting of jetting plumes.

Ecumenicalism is portrayed through abstract symbols at the Four Chaplains Memorial Fountain at National Memorial Park in Falls Church: Two protestants, a rabbi and a Catholic priest were aboard the troop transport "Dorchester" when it was torpoedoed in the Atlantic in 1943. They gave up their life jackets and stayed to comfort the dying, then locked arms and prayed as the ship sank into the sea. The fountain is under repair. FOUNTAINS OF FRIENDS

Also at the Falls Church cemetery is the Fountain of Faith, with 37 hovering bronzes sculpted by Swede Carl Milles. Each life- sized figure and represents a person Milles knew who died and, he believed, has been happily reunited with fellow souls beyond the veil. The work is about the size of a basketball court.

The courtyard of the Moslem mosque at Massachusetts Avenue N.W. has a small pink-and-gray marble fountain. Nestled like matching mixing bowls, each basin collects the spill from the one above. Underwater tiles match the lacy, cerulean mosaics beneath Arabian Nights arches. LIGHTS IN LIMBO

Other striking mosaics reproduce ancient Mexican, Peruvian and Gautemalan designs in the patio of the Organization of American States. At the center of this exquisite skylighted space is the Aztec Fountain with its feathered serpents and hieroglyphics by Gertrude Vanderbilt Whitney (1910). At the time it was a technological wonder; its keyboard-controlled lights and colors played against the falling water on Latin holidays. Alas, the controls haven't been tried in a long time, says an OAS staffer, and may not work (guided tours 9:15-5:15 weekdays.)

Cost of repairs, energy or personnel cutbacks kept many a fountain quiet last summer, so before visiting, call the source. Fountains at the Kennedy Center, for instance, usually bubble only before a performance. The two-block fountain in front of the Martin Luther King Library runs capriciously. The Meridian Hill Cascades are frequently down for repairs.

Worse yet, many of the ones working today may be dry tomorrow. Steve Tatti particularly fears for the Dupont Memorial Fountain. French's white marble sculpture of wind, sea and stars is eroding. "Marble is soft, too susceptible. It needs to be brought inside and a replica placed outside."

Many fountains and outdoor statues have been stored, not for their own good, but to make room for more outdoor art. A statue of Rear Admiral du Pont (his last name is misspelled on his memorial) was stored to make room for his fountain. The Truxtun Fountain, which once sat in its own traffic circle at 8th and K NW, was shouldered aside by the public library. CAPITOL PLEASURES

Inside, where it was always meant to be, is the charming Indian Fountain sculpted by William Rinehart in 1857: Elliott Carroll, Architect of the Capitol, has the 13-inch bronze in his personal office; we can see it when he's not in.

Also under his jurisdiction are the fountains by Frederick Law Olmsted, the landscape architect of the Capitol in the 1870s and '80s. Two flank the Capitol's East Plaza and a brick grotto, Carroll's favorite, enclosesns hi what once was a spring on the northwest side of the Capitol.

Carroll also presides over the west side Hemicycle, over which President Ronald Reagan stood when he took his oath in January. "No dips for him. The fountain was off then and boarded over."

The area's second Hemicycle, at the entrance to Arlington Cemetery, is not working, says John Byrne, superintendent of the George Washington Parkway, because it would cost too much to repair the plumbing. It's too bad, he says. "An active fountain is worth it. A living, moving piece of architecture. I love them."

Other fountains share the Hemicycle's fate: Lady Bird Johnson Fountain once floated in the Potomac off Hains Point, but its Rolls-Royce engines kept burning out and cost too much to fix. THE DIRTIEST TRICK

L'Enfant Fountain, once the glittering centerpiece of the plaza, leaked into the garage below, "so they filled the fountain with dirt," said Goode. "It was one of the most successful architectural experiments. It relieved the concrete; now it's lost." STAR LORE

A last trickle of trivia: ABC Washington bureau chief John Hermes Secondari wrote the novel "Three Coins in the Fountain," from which sprang the movie and the 1954 Academy Award-winning song.