What was going on when I was born?

The Marsh & McLennan Companies accumulated some $2 billion in government bond positions, in large part as a result of unauthorized trading by one of its dealers, the company said yesterday. The positions were significantly larger than the company realized it held. The figure was also considerably more than the $1 billion or so Wall Street experts had guessed after the company announced on Monday that it had lost some $120 million as a result of the unauthorized bond trades, or about $60 million after taxes. The charge is to be taken against first- quarter profits.

Charterhouse J. Rothschild P.L.C., one of London's newest and most broadly based financial services companies, today announced a preliminary agreement to acquire Hambros P.L.C.'s 24.8 percent stake in Hambro Life Assurance P.L.C. as the first step toward a merger with the insurance company. The merger would bring together Jacob Rothschild and Hambro's Mark Weinberg, two of the most dynamic executives in the City, London's financial district. In addition, the two men say, the merger would create an enterprise with enough capital to take on the large financial services groups being formed in Japan and the United States by deals such as this week's agreement by Shearson/American Express to acquire Lehman Brothers Kuhn Loeb.

''The Council President is behind the times. The Department of Transportation is in the final stages of preparing a major citywide street repair initiative that will be announced Monday.

Cell 72 was typical: a concrete room about five feet wide and eight feet long, illuminated only by the narrow shafts of light that filtered through small holes near the ceiling. The door was steel. There were no windows but on one wall ?former occupant had drawn himself one, complete with bars. Other occupants had scratched their names into the walls or etched off the days. And there was one inscription, in letters about two inches high, written in blood. It read, in French, ''God save me.''

Stephen King is the author of 13 books, including ''The Shining'' and most recently, ''Pet Sematary.'' A TRISKAIDEKAPHOBE is one who fears the number 13, and this is not a good year for the triskies, of which I am one. Living through a year with such a reputation as George Orwell has given this one is bad enough, but consider this added fillip - for only the 27th time since the year 1800, we are living in a year with three Friday the 13ths, the maximum possible. One fell in January, one falls in April (note, that's tomorrow) and the third occurs in July.

AGNES MYERS is 87 years old, likes martinis, says she was ''born in Michigan so I wouldn't have to be born in Ohio'' and that she is quite happy in her retirement in Kendal-Crosslands, a continuing-care community near Philadelphia. In a hospital setting with full medical care she is able to live in comfortable quarters with some of her own furniture. Bea Peyton is 69, proud to be part of a volunteer 24-hour emergency rescue team in the huge Sun City Center retirement community south of Tampa, Fla., proud of her cardiopulmonary resuscitation training, which she says is a ''far cry from being a Lake Superior housewife who occasionally went bowling.''

''Here's how I read,'' Stewart Wiggins said. He picked up a small lens that was wired to a device that resembled a tape recorder. It was called an Optacon. He deftly ran the lens over a computer printout while he stuck his left index finger into the tape recorder-like device. As the lens swept over sentences, the device vibrated. Mr. Wiggins has been trained to translate the vibrations into words. Mr. Wiggins, 49 years old, works as a computer programmer here in Wilmington for E. I. du Pont de Nemours & Company. Late in 1972, a benign tumor was removed from his optic nerve. Ever since, he has been blind.

The impact of Latin America's foreign debt crisis reaches far beyond the board rooms and balance sheets of America's biggest banks. It is also felt in a sunny, spacious office on the third floor of the First Wisconsin National Bank. The man who works here, Christoph H. Guenther, an executive vice president and head of the bank's international department, has been lending First Wisconsin's money overseas for 27 years. The last two have been particularly trying.

The Hebrew Home for the Aged in Riverdale is being turned upside down these days in preparation for the Passover holiday that starts Monday night. A special set of dishes is being brought up from the basement, the ovens are being dismantled for scouring and no sofa is being left unturned in the search for bread crumbs. For most of the 1,100 residents of the home, where the average age is 80, all of the activity is familiar. It is what they and their families have always done before Passover - only on a bigger scale.

To clinch the last-minute financial rescue package for Argentina at the end of March, the Federal Reserve Bank of New York assured the 11 American and foreign commercial banks that they would be repaid the $100 million that they were asked to lend the ailing Latin American nation, banking sources said yesterday. This unwritten assurance not only persuaded the five American and six foreign banks to participate in the overall $400 million package but also convinced them to lend at an extraordinarily low interest rate, the sources said. They added that there was little risk for the Fed itself because it had been authorized by Argentina's central bank to debit Argentina's dollar account at the Fed at the end of June, when the banks are scheduled to be repaid. Argentina is reported to have about $1 billion in readily available foreign-exchange reserves and about $2 billion in such longer-term assets as gold.

City Council President Carol Bellamy accused Mayor Koch yesterday of failing to deal with the city's pothole problem, touching off an exchange of increasingly bitter personal insults. By the end of the day, Mr. Koch had called her ''the arch bomb thrower'' who ''can't think of anything herself,'' and she had said that he should spend more time doing his job and less ''peddling his book.'' At 5:30 P.M. Mr. Koch issued a statement saying he was ''declaring a unilateral Lebanese cease-fire.'' It came after a day in which Miss Bellamy had held two news conferences and issued two statements and Mr. Koch had held one news conference and issued two statements.

THURSDAY, APRIL 12, 1984 The Economy The House approved a $49.2 billion tax bill as the first concrete step by Congress to reduce Federal budget deficits. The bill is intended to close loopholes and raise taxes on liquor and diesel fuel. Debate on a similar bill continued in the Senate. Both bills differ from plans proposed by President Reagan. (Page A1.)