Harper's magazine -- founded in 1850 when shoguns still ruled Japan, an emperor governed Brazil, California was a few months away from admission to the union and the slave trade was be outlawed in the District of Columbia -- is going out of business.

The nation's oldest monthly magazine will stop publication after its August issue because of rising losses, its parent the Minneapolis Star and Tribune Co. announced today.

The Star and Tribune had been looking for a buyer for months, but Harper's losses -- reportedly more than $1.5 million last year -- frightened away all comers.

"Despite the fact that Harper's has achieved widespread recognition for its independence and editorial excellence under Lewis H. Lapham's editorship, it was no longer desirable for the company to support its operation in the light of increased costs of such items as paper and postage," Otto Silha, Star and Tribune chairman, said in a statement on Harper's demise.

"At the same time, we were unable to reach a contractual assurance that qualified buyers would finance the magazine's long-term continuance," Silha said.

One potential buyer said recently that after looking at Harper's books he knew it could not be run profitably. "I would have had to close it down for the advantages of taking the loss, he said.

That is what the Star and Tribune decided to do today.

Harper's has a circulation of 325,000, but it carries little advertising and had suffered over the last 15 years from competition from a wide range of specialty magazines. General-interest magazines such as Harper's watched more and more Americans fill their magazine racks with upstart publications, concentrating on the narrower fields that seem to be their main interest.

Time had worked many changes since 1850 when Harper's in its first issue, noted a rising interest in monthly literary magazines. The French poet "Lamartine has just become the editor of a newspaper. Dickens has just established a weekly journal of his own, through which he is giving to the world some of the most exquisite and delightful creations that ever came from his magic pen," Harper's said.

The leading article in that first issue was the beginning of "Maurice Tiernay," a military novel by Irishman Charles Lever, whose books are full of battle, enthusiasm over military glory and cries of "gallant fellow!"

In its last issue, Harper's will feature an article on modernist fiction, one on the gold standard and one on officially sponsored culture, editor Lapham said.

"It was a fine and illustrous institution," Lapham said. "My mood is sorrowful."

Lapham was the last potential buyer to negotiate with the Star and Tribune, and he made an offer which the parent company refused."They didn't think there was enough money behind my offer," he said.

Over its history, Harper's has published almost every famous writer of short stories.

Mark Twain made his first sale to Harper's as did Sherwood Anderson. Rudyard Kipling, Joseph Conrad, Willa Cather, G. K. Chesterton and Aldous Huxley wrote for Harper's.

And so did others no longer well known, like Mary R. S. Andrews, Israel Zangwill, Brand Whitlock and Mary Heaton Vorse.

The magazine also published Charles Dickens, William Makepeace Thackeray, Wilkie Collins, Conan Doyle and the novels of many others in serial form.

On its 75th birthday, Harper's transformed itself in response to what must have been one of the earliest of reader surveys.

Harper's asked its subscribers if they would like the magazine to drop its illustrations and replace them with more articles. The subscribers said yes and Harper's redesigned itself, complete with a bright orange cover so that it could boast it was both the oldest and newest magazine in America.

Whatever Harper's did, however, it didn't make money. By Lapham's readers were difficult to define. Not all of them were as enthusiastic as former president of American Telephone and Telegraph Co. Theodore Vail, who said: "I got more of my education out of reading Harper's magazine that I did out of all the school books I ever studied." But they were, by and large, loyal.

"Harper's was a success with its readers, but not with its advertisers," Lapham said.

In 1958, Harper's conducted a survey to find out more about its readers. Not surprisingly, more were city people -- only 2 percent were farmers. More lived in California than in any other state. Over half had done some graduate work and 40 percent had graduate degrees.

Their annual income was twice the national median, and their median age was 42.

The audience was the "one percent of the population which might be described as the decision-makers, opinion-formers and pace-setters," concluded John Fischer, Harper's editor at the time.

Increasingly, however, advertisers found the Harper's audience too difficult to define. They couldn't predict whether the Harper's reader was interested in whiskey, cars, power tools, sports clothes or any combination of the above. In the magazine business "skinny breeds skinny" -- a magazine thin for lack of advertising tends to stay thin because advertisers shun it.

The death of Harper's leaves Atlantic Monthly alone in the general monthly magazine field. While the Atlantic also is ailing, it was recently purchased by Boston real estate developer Mortimer Zuckerman, who has pledged to revive it with new capital.

In the short run, Harper's collapse will hurt the Atlantic because they jointly own an advertising entity. In the long run, however, the death of its elderly competitor may be good news for the Atlantic, which is only 123 years old. CAPTION: Pictures 1 and 2, The magazine's flag as it appeared in December 1860 and this month.; Illustrations 1 through 3, Civil War drawing by Winslow Homer, published in October 1864, was one of many illustrations carried by Harper's in earlier years. Other cover concepts are December 1860 and this month.