The telephone has its moments, but the most American of inventions is the salad bar. It is democratic, giving everyone a chance to be a chef. It is efficient, cutting staff needs and allowing diners something to do while they wait for the roast prime ribs of beef au jus. It is a tribute to American ingenuity, abundance, diversity and, sometimes, originality. Finally, it has a certain imperialist tendency to take over where it was meant to accompany or serve. It is, however, less demanding than the telephone.

We asked Washington's diners for their favorites and were flooded with answers. The two public favorites, by far, were Zachary's and Fiddler's. But also in the American tradition, they stuffed the ballot boxes -- Zachary's by handling out slips of paper with a plea to write The Post, and Fiddler's with a petition tacked over the salad bar.

Here, for the next two weeks, is a survey of the most popular and three that sounded particularly original, plus a list of nominations that I did not visit, there being only so much iceberg lettuce a person can be expected to consume in the line of duty. Zachary's, 6238 Old Dominion Dr., McLean, 821-1976.

Loyalty is said to be a declining emotion, but Zachary's followers are as zealous as any patriot. It is, indeed, as warm and friendly a little restaurant as one encounters in suburban shopping centers. Staff members address you by name and inquire about the state of your health and family, though the waiters push unnecessarily hard to sell extra appetizers and drinks.

Zachary's is Greek and moderately priced and bright red, with dark wood booths. The menu centers on lamb, grilled fish, beef tenderloin and a few fragrant, typically Greek casseroles, all perfumed with garlic. Perhaps the best dishes, however, are the appetizers (spanakopita, sausage, squid) and desserts (baklava and creme caramel), which is too bad because there are free appetizer dips on the salad bar, and dessert is unnecessary after the large portions. You can spend as little as $8 or as much as $25 for a complete meal, or about $5 for the salad bar alone.

What sets this salad bar apart are those appetizers -- dips of yogurt with cucumbers, potato, eggplant and salty orange roe -- to be scooped with toasted pita bread heavily salted and herbed. The dips are decent rather than great, and so intense with garlic that your mouth burns on occasion. The greens are mostly iceberg lettuce, but to mix with those are pungent pointy black imported olives, green olives, several kinds of onions, long hot green peppers, beets, and the inevitable Bacos, as well as two kinds of cheese -- grated parmesan and tastier feta. Hardly Greek, but a change of pace from corn relish; the white bean salad is a more authentic addition. The quality of the goods is, except for the excellent black olives, standard.But the containers are kept filled and the ingredients fresh. The large plates are cold, and there are two dressings -- very cheesy blue cheese and a more distinctive oil-vinegar-oregano mixture. Fiddler's, 4340 Connecticut Ave. NW. 244-0881.

Nearly opposite from Zachary's is Fiddler's salad bar. It is big. It is flashy. It is full of everything under the sun, from Pennsylvania Dutch-style watermelon pickle to carrot raisin salad -- about 30 ingredients, with six dressings.

Fiddler's is a glass-walled contemporary showpiece, filled with plants. And the menu runs the gamut from stroganoff burgers to ribs and chicken, with none of it nearly as good as the salad bar, which can be ordered alone for $4.95. And should be.

The plates are large and refrigerated. The dressings, particularly the yogurt herb, are zesty. The salad fixings look fresh, the fruits are ripe, and the bowls are frequently replenished. In fact, the most serious complaint I could make is that the pieces of lettuce and cauliflower are too big to be gracefully eaten. But that is easily remedied at the table, and an original concoction can be culled from the spinach, cucumbers, hot pepers, mushrooms, alfalfa sprouts, black-eyed peas and olives. The croutons are homemade from giant loaves of rye and pumpernickel. Three different carrot salads were present one day, along with peas-and-carrot salad, cottage cheese, sauerkraut, coleslaw and corn-pepper relish. Then there are the fruits: melons, oranges, grapefruit and, one day, canned peaches and apples. Fiddler's is one of those salad bars that is just short of soup-to-nuts. G. D. Graffiti, 1321 Rockville Pike, Rockville. 424-4091.

G. D. Graffiti's salad bar even includes the nuts -- the seeds, six kinds. Still, one wonders how many times a waiter can go through his "I'm your bagman" routine at the gangster-theme restaurant before he loses his appetite? The customers never seem to lose their appetites, and continue to put up with a wait in the dreariest bar this side of Casablanca, the tiredest bag of jokes ever found in a comic's trash bin, and Italianesque food tamed for the masses. There is only one reason to return to Graffiti after being through the caper once, and that is the salad bar.

The menu calls it an Italian Fruit and Vegetable Stand, and that is no exaggeration. Vegetable garnishes for the greens number more than 20, from alfalfa sprouts to raw zucchini and summer squash, from raw green beans to whole white radishes. The greens themselves are a nice mix of romaine and spinach in with the iceberg, though soggy, decaying leaves are here and there. A unique addition is the seeds and nuts, but the stunner is the fruit bar, all fresh, ripe and dripping juices, from four kinds of melon to mangoes and kiwi fruits, pineapple, Bing cherries, apples, pears, oranges and grapefruit.

Graffiti keeps its large oval plates cold. The two nearly identical lines keep the pace fairly rapid. Ingredients are replenished frequently, and most of the foods look fresh (except for yellowed broccoli and brown-tinged bean sprouts found one day). There are seven dressings, none memorable and none dreadful. Two are sweet in case you want to dress your fruit, and one clever touch is "undressing," wedges of lemon and lime.

Besides the glorious fruits, a commendable characteristic of Graffiti's salad bar is that is is just fresh fruits and vegetables, nuts and seeds (with olives, of course, being canned). There is no fakery of Bacos, no gummy macaroni or potato salads, no cheese that was grated too long ago, no stale croutons. Graffiti attempts no more than it can do well. And the bread is homemade long soft rolls modeled after breadsticks.

You don't have to order dinner, for the salad bar alone is available for $4.45, or just the fruit bar for $1.95. Main courses plus salad bar are $7 to $10. J. R.'s Steak House, 940 Lee Hwy., Fairax. 591-8447.

J. R.'s is not a contender in the great steakhouse sweepstakes. Despite the menu's spiel about its carefully selected and naturally aged beef, the meat on the plate is just ordinary. J. R.'s -- dim and baronial, with comfortable leather-look chairs on rollers -- is probably best known for its salad bar (at the Fairfax branch only).

With the iceberg-based mixture of greens are 23 garnishes, a well-stocked array of cucumbers, green peppers, tomatoes, two kinds of beans, two kinds of olives, two kinds of pickles, two kinds of hot peppers, two kinds of nearly everything. The cheese is shredded cheddar, the bacon clumps of what seems to have been canned. Grated egg is an appetizing touch, but in general this is a straightforward, predictable salad complex, which is enhanced by its offer of large, deep, translucent plastic bowls that make it easy to toss your selections. The five dressings are hard to tell apart, but there is oil and vinegar if you like to avoid taking chances on mysterious creamy mixtures.