Publishing magnate S. I. Newhouse Jr. yesterday offered $119.5 million to buy The New Yorker magazine, the toney weekly compendium of reporting, fiction, poetry and cartoons that over the years has attracted some of the literary world's brightest lights.

Directors of New Yorker Magazine Inc. met for several hours yesterday to consider the offer. The board then adjourned, saying it would consult with the company's lawyers and investment bankers before making a decision. Should the board reject the bid, Newhouse could choose to take it directly to the owners of The New Yorker's 800,000 shares.

Newhouse's offer is for $180 a share. Yesterday, New Yorker stock, which trades over the counter, closed at $176-bid. Last fall, the thinly-traded stock was selling for about $140-bid.

Newhouse, whose family's Advance Publications Inc. empire includes Random House book publishing, Conde' Nast magazines and newspaper and broadcasting interests, bought 17 percent of The New Yorker for $25 million three months ago and said at that time that he had "no plans to seek control of The New Yorker or to influence its management."

Newhouse could not be reached for comment on why he had changed his plans for the company. When he bought the stock last November, many analysts speculated that Newhouse would not attempt to buy the company until the death of Chairman Peter F. Fleischmann, head of The New Yorker's founding family. The family owns 32 percent of the stock and is the company's largest shareholder. No other shareholder owns more than 1 or 2 percent of the company, according to New Yorker officials.

Some analysts have expressed concern that The New Yorker would lose some of its independence and informal management style if it was bought by a publishing conglomerate. "One hopes that, if Newhouse is successful in this, that it won't portend any change in the editorial excellence or independence of The New Yorker, for which it is justly famed," said John Morton, a publishing-industry analyst with the Washington office of Lynch Jones & Ryan, a securities firm.

Yesterday, in a letter to The New Yorker's board containing his $180-a-share offer, Newhouse said Advance would operate The New Yorker "on a stand-alone basis as a separate company" with the magazine and all its business and editorial departments remaining independent. (Advance's Conde' Nast unit publishes a number of magazines, including Vogue, House & Garden, Gentleman's Quarterly and Vanity Fair.)

"We recognize that the unique quality of The New Yorker magazine is the product of its personnel and of their operating practices and traditions, including the tradition of complete editorial independence: the editors' having total control of the magazine's editorial character, policies, procedures and content," Newhouse wrote. "We wish to preserve its quality through maintaining its personnel and its traditions."

Longtime New Yorker theater critic Brendan Gill, author of "Here at The New Yorker," an anecdotal history of the magazine, said yesterday that he didn't expect Newhouse, whom he described as a good friend, to intefere with the magazine's editorial or business independence. Pauline Kael, the magazine's movie critic, described any speculation about possible editorial changes at the magazine should Newhouse take over as "wildly premature."

Founded in 1925, The New Yorker has served as the home for scores of great writers and artists, including James Thurber, John Updike, Charles Addams and Saul Steinberg. Hundreds of books have gotten their first exposure between its covers as long articles, and its reviews of movies, books and the performing arts are widely quoted.

Its perennial cover boy, staid Eustace Tilley, has become a symbol of the magazine and its generally high-income readership -- the New Yorker's 480,000 subscribers are considered one of the highest-quality circulation bases in the publishing industry. "The New Yorker is one of the most successful advertising vehicles in the magazine industry, and would, I think, be a property any company would love to own," Morton said.

In 1983, the last year for which figures are available, the New Yorker's parent company posted $74.7 million in annual revenue, from the magazine and other holdings, including a printing company, two small magazines, and part interest in a company that makes computer terminals.

Last year, The New Yorker was wracked by change and controversy. In addition to the purchase of an interest in the company by Advance, the company named a new president, J. Kennard Bosee, while longtime editor William Shawn, 77, only the second editor the magazine has ever had, appointed two assistant managing editors who were viewed at the time as his potential successors.

The New Yorker's reputation for solid reporting and a devotion to accuracy was shaken last summer when it was disclosed that Alastair Reid, a frequent writer for the magazine, had changed a few of the facts in some stories he had written for The New Yorker.

New Yorker officials downplayed the Reid incident -- although they tightened internal controls -- and in interviews late last fall they seemed unconcerned about Newhouse's interest in the magazine.

"The managers of the corporation really have no say over its ownership," Bosee said. And Shawn said, "I don't know what the developments might be in the future. I am certainly keeping my eye on everything." CAPTION: Illustration, New Yorker Magazine Inc. financial results for 40 weeks ended Nov. 6, 1984: revenue $58.1 million, net income, $3.1 million ($3.66 a share), assets $45.6 million (unaudited). Employes: 305.