In the Footsteps of Saint-Exupery

WALKING tours have become a bustling and imaginative industry. As the weather begins to turn warm, tours proliferate to the point where it is possible, as it is this weekend, to choose from walks in most of the boroughs with a staggering variety of themes. New Yorkers now know a good deal more about the city's nooks and crannies and its cultural and social history. But each season there are surprises.

This Sunday, for instance, it will be possible to relive the life of the French author Antoine de Saint-Exupery as he wrote ''The Little Prince.'' ''In the Footsteps of 'The Little Prince,' '' one of four tours offered by the 92d Street Y this weekend, takes tour members through the streets Saint-Exupery walked at night and past the restaurants and homes he and his wife frequented during a stay in New York City from January 1941 to April 1943. ''He's a New York author, crazy as it sounds,'' Howard Scherry said. Mr. Scherry, a Saint-Exupery scholar, will give the tour this Sunday in English and next Sunday in French.

One of the pleasures of walking tours is the chance they frequently offer to spend time with men and women whose love for the city and curiosity about life itself have led them to become guides. Mr. Scherry speaks with such eloquence and humor about Saint-Exupery that it is hard not to imagine the two as lifelong friends. He talks with authority of Saint-Exupery's friends and colleagues, many of whom Mr. Scherry has sought out and befriended in a process that might be likened to a treasure hunt.

The three-hour tour will proceed from the Upper East Side down to midtown Manhattan and back up to Central Park, with two rest stops. Mr. Scherry will point out some 50 sites and actual buildings, including some examples of handsome landmark architecture, each, it seems, with a colorful anecdote of its own. There will also be references to places outside the city, like the home of Charles and Anne Morrow Lindbergh in Lloyd Neck, L.I., where Mr. Scherry believes Saint-Exupery may have seen the prototype of the Little Prince in the Lindberghs' young, golden-haired son Land.

Their friendship ended, though politely, when the influential American aviator began to preach isolationism. Saint-Exupery, whose love of flying inspired his ''Night Flight,'' ''Flight to Arras'' and ''Wind, Sand and Stars,'' had come to the United States in part to urge that America end its neutrality and enter World War II. ''Saint-Ex,'' as his friends called him, had joined the French Air Force when the war broke out, leaving France when it fell to the Germans. He returned to duty in 1943 and was lost, at the age of 44, on a reconnaissance mission over the South of France the following year. Childhood and Mother

Mr. Scherry will talk of ''Wind, Sand and Stars'' and its influence on ''The Little Prince.'' He will also discuss the author's childhood and his intense affection for his mother, which Mr. Scherry suggests makes the tour particularly appropriate for Mother's Day. He will talk of the friends and childhood memories that Saint-Exupery wrote into ''The Little Prince.''

On the Upper East Side, he will point out the home of Bernard Lamotte, Saint-Exupery's friend and illustrator, at 14 East 75th Street, and the home of Raoul de Roussy de Sales, a journalist and friend, at 755 Park Avenue, at 72d Street. ''He tried to convince Saint-Exupery to become a Gaullist,'' Mr. Scherry said. ''He refused because he said he was only interested in fighting Vichyists. He called the exiles who bickered to him about it the 'Fifth Avenue Resistance Fighters.' ''

Mr. Scherry will also talk of a trip Saint-Exupery made with Lamotte to buy an organ at the Aeolian Organ company on 57th Street. ''Saint-Exupery loved classical music,'' Mr. Scherry said. ''He set out to buy an organ with Lamotte but ended up buying a dictaphone.'' The organ, it seemed, cost $12,000 and the dictaphone only $700, and Saint-Exupery foresaw it would be useful in dictating to his secretary.

At 221 West 57th Street, Mr. Scherry will talk of ''A Message to Young Americans,'' a talk Saint-Exupery gave to the Progessive Education Association. ''Little do the teen-agers who go the Hard Rock Cafe know that he gave a talk just next door!'' Mr. Scherry exclaimed. Too Comfortable to Pray? The tour will pass St. Patrick's Cathedral, where Saint-Exupery attended Christmas Eve mass in 1942, with Robert Boname, a friend. ''He found the church very warm, and wondered how they could genuflect and pray if they felt too comfortable,'' Mr. Scherry said. '' 'To feel oneself near God,' he said to Boname, 'it is necessary to have a little the impression of catching pneumonia.' ''

There will be a stop at 35 Beekman Place, one of the homes found for the Saint-Exuperys by the wives of his publishers, Eugene Reynal and Curtice Hitchcock. At 42d Street and Fifth Avenue, there will be a glance south toward the Empire State Building, which Saint-Exupery delighted in visiting with friends. There he would toss out bits of paper and watch them float and twirl like airplanes.

And then the tour will wind uptown again toward 240 Central Park South, where the Saint-Exuperys lived for a year and a half. ''He loved that apartment,'' Mr. Scherry said. ''It was a penthouse, and he said it was almost like being up in a plane.''

''In the Footsteps of the Little Prince'' begins at 1 P.M. Sunday. Admission is $16. Reservations are necessary for this and the 92d Street Y's three other tours this Sunday.

''Great Historic Disasters of New York'' is a four-hour tour of the sites of historic fires, riots, battles and other disasters. It will be conducted by Gerald Wolfe, beginning at 11 A.M. Admission is $16. ''Musical Instruments of the Metropolitan Museum'' is a five-hour tour of the museum's musical-instrument collection and workshop. The tour will be conducted by Stewart Pollens, associate conservator of instruments at the museum. It will beginat noon and will include a performance by the New York Chamber Symphony of music by Ravel and Stravinsky. Admission is $25.

''The Villages: The First Suburbs'' is a three-hour tour of neighborhoods that were New York's suburbs of the 1830's. The tour will be conducted by Barry S. Lewis, beginning at 1 P.M. Admission is $14. Information on all Y tours, meeting places and reservations: 415-5424. Charge: 415-5698.