As a souvenir of last nights's birthday party celebrating Smithsonian magazine's 10th year, guests received a manila envelope with a copy of the magazine's first issue inside.

"I was absolutely horrified to discover the magazine has recirculated," Smithsonian secretary S. Dillon Ripley told the crowd of some 500 gathered at the Smithsoninan's Arts and Industries Building. "I assure you there is no symbolism connected with the cover," which is a photograaph of two courting elephants. "I understand the Democratic Convintion is in 10 days or so."

"Despite the secretive brown wrapping, which looks to me as if you have been to a pornographic store," said Ripley, "the magazine is a nice publication, clean, healthy, wholesome. It has to do with Americanism. It has to do with the American dream."

After his remarks to the crowd, Ripley, like a proud father, gathered staffers around the 10-tier cake decorated with proofreaders' symbols. "Come on, staff. . . Jerry. . . Ann. Come on, kids," he said, blew out the candles and launched into "Happy Birthday."

"There's the bride and the groom cutting the cake," said one woman as Ripley and publisher Ed Thompson, who got the magazine started 10 years ago and is still one of its editors, sliced through a paragraph mark.

Editor Ted Park reminisced about the magazine's first birthday. "The first party was held by my wife at our little house in Annapolis," he said.

"But we knew everybody then," said his wife, Jean, as she glanced at the 500 guests feasting on lavish fruit and vegetable trays.

Park recalled the early days of the magazine, when the six-member editorial staff "knew each other very well and our emotions all hung out. There were always moments of panic or despair that would spread through the office like wildfire."

Free-lance writers contributed to much of the turmoil, he said. "Their copy would always come in late and short, and we'd have to make it up ourselves."

Meanwhile, free-lancer Dora Jane Hamblin said that when she began her first assignment for Smithsonian, Thompson told her, "'As for money we pay the same as a high-class plumber.' I had no idea how much that was, but I said okay."

Magazine legend has it that Thompson is an acute mumbler, and he refreshed staffers' memories last night as he mumbled inaudible thank-yous to Ripley for his support of the magazine throughout the years.

In the come-and-go economics of the magazine business, 10 years is a respectable lifespan verging on institutionalization.

"Lots of things go good for you when you're young," said acting publisher Joe Bonsignor of the magazine's first decade. "To keep the same verve you had in your first 10 years during the next 10 years is the challenge."

Ripley said the magazine, by itself, is not an institution. He called it an "umbilical line" to the associates from the greater parent organization, the Smithsonian Institution."In the meantime, the message of the magazine has to do with America. And it's not going to go away unless America goes away. t

"I was opposed to the magazine," said Ripley, "I thought it was going to be too much trouble. But it's like getting born or something. It's all ghastly. But once you're born it's all right."