Melvin Jasper Sr., a tractor-trailer driver for Giant Foods, was leaning back in his brown leather recliner. His job was done; 25 pounds of spare fibs cooked and smothered in his special sauce, and, for a moment, he ignored his wife Anne's orders to spread newspapers over the table for the steamed crabs.

Instead of moving, Jasper was basking in the wideeyed attention of his grandson, Kenji, 3, who was listening to Granddadreminisce about Fourths. "My wife and I grew up in Georgetown and we never had a back yard. We had to go to the sand barges and the P Street Beach, what we called the Hallow, for our outings. So as soon as we had a back yard, we started having the family over," said Jasper, his tone reflecting his satisfaction as he checked out his jeaned clan.

For the last dozen years the Jaspers have lived in the Fort Dupont area of Southeast, with a sloping yard large enough to accomodate 20 relatives and friends.

Finally the gentle urgings of his wife got to Jasper, a tall, muscular man dressed in brown running shoes, white shorts and a brown tank top. The crabs, purchased at dawn yesterday at the Maine Avenue waterfront, were moved outside under a vinyl umbrella and the early arrivals -- two sons, wives, girlfriends and friends -- sat down. The ribs smoking on a nearby grill.

Kenji, the son of Jasper's oldest child, Melvin Jr., a graphics designer, was trying to get everybody's attention, tugging at a crab. Granddnd took the bait. "I just opened it, I opened the crab," bellowed Kenji. Jasper Sr. answered, "One day you'll be strong enough to do the whole thing." Kenji insisted, "But I did it now." And everyone else insisted it was too damp to sit outside any longer and moved toward the second food table inside.

As Anne Jasper finished slicing a hummingbird cake, dark as a spice cake with nuts, pineapple and bananas, Jasper Sr. made a run to the liquor store. His wife, a tall, ample woman with a jet-black Afro, was concerned about the weather. "I just hope it crears up because I don't like to eat crabs in the house. They smell she said, indicating she was practical, not complaining. She and her sister, Bernice Gibson, reminisced about the Fourth when their mother spent the night in the hospital after a neighborhood bully burned their younger brother's hand with a firecracker. "To this day, when I see that man, I think of that," said Mrs. Jasper.

Sally Langley, a Jasper in-law and a hostess for the Macke Vending Co., had a Fourth story. "When I was growing up in Powhatan County, Va., nar Richmond, there wasn't much to do. So on the Fourth we used to get all dressed up and thrash the wheat. It was an occasion, lots of food, fun and drink."

At every family gathering there's a moment when everyone notices a youngster who has shot up a foot or is beginning to show signs of womanhood. Angela Bell, 15, a neighbor, was the exclamation point yesterday. Jasper Sr. simply said hello and smiled. Jasper Jr. walked right by at first and twirled around to exclaim, "You're Angela, you're the person who used to . . ." and he didn't finish. Michael Jasper, 21, a student at Morgan State University and a lifeguard, said, "Yeah, I recognize her. How's school Angela?" Before Angela had to crawl under the table, Dwayne Shaffer, 2, came along and shot everyone with a Star Wars gun.

Then the party divided between the "General Hospital" watchers and the dancers. Angela Jasper, a daughter-in-law, and Tony Langley, her brother, danced to the Isley Brothers. Anne Jasper told a friend about going to a disco, complained about the noise there, and then searched her memory for a song she liked. Someone supplied the answer, "Marvin Gaye."

When Estelle Bell, a neighbor, arrived with her spaghetti salad, the second round of eating started. And Jasper Sr. found a willing ear to complain about his sons' reluctance to fix their cars. "Remember that day I told you Michael was getting new tires? Well, he know they will rot?" Jasper sighed, said something about how they took after his wife, and went back to his recliner with a resigned grin. CAPTION: Pictures 1, 2, and 3, Three faces on the Fourth: Linda Bezich, Gustavo Jimenez, Kenji Jasper; by Gerald Martineau, Lucian Perkins, Joel Richardson -- The Washington Post; Picture 4, The Jasper family eats dinner under a back-yard umbrella; by Joel Richardson -- The Washington Post