August 17, 1982

IN Brooklyn a young mother threw her hours-old baby out of an apartment window to the street 18 floors below. In Tokyo the corpse of a newborn child was abandoned in a coin locker in a railway station. In Manhattan a father beat his 3 1/2-month-old son to death. These are a few of many reported cases of infanticide, the most vicious form of child abuse. It is a human crime so abhorrent and disturbing that little has been written about it, and it is behavior so mystifying that scientists are still far from fathoming its underlying causes. Scientists agree that the history of human infanticide probably goes back to the cave. Records from medieval times show that a parent would kill either male or female infants, depending on which sex was needed more in society at a particular time in history. And in some primitive cultures today infanticide is not an uncommon practice.

A senior Navy admiral has questioned the legality of a $4 million fee that the McDonnell Douglas Corporation plans to pay a Spanish consultant for helping to sell F-18 jet fighters to the Spanish Government. Vice Adm. E.R. Seymour, the head of the Naval Air Systems Command, said in a Feb. 5 letter to the Chief of Naval Operations then, Adm. Thomas B. Hayward, that the terms of an agreement between McDonnell Douglas and its Spanish agent, Compania Aeronautica Espanola, appeared to exceed limits set by Government regulations. The main issue centers on whether the payment to the agent is made out of the company's profits or whether it is counted as part of the price of the $3.1 billion contract that is being financed with Government credits.

The United States and China have signed a new communique governing both countries' relations with Taiwan. Administration officials say the document should prevent a major rift with Peking. In the communique, expected to be made public on Tuesday, China pledges to seek reunification with Taiwan only by peaceful means, and the United States promises not to exceed current levels of sales of fighter aircraft to Taiwan and to reduce them gradually. John H. Holdridge, the Assistant Secretary of State for East Asian and Pacific Affairs, gave unpublicized briefings this morning to Senate and House leaders in advance of the public announcement of the new development in Chinese-American relations.

Scientists, using a combination of machines and detectors built on a monumental scale, are now ready to launch into a whole new world of physics. In scope and complexity, their project bears much in common with man's missions into space. The goal is to find what the scientists refer to as the missing ''keystone'' in the family of particles that seem to constitute and control matter at the most basic level. The celebrated keystone is a triplet of particles that, it is believed, will fit into what otherwise appears to be an orderly theory of matter and the universal laws that govern it. These three relatively massive, though elusive, particles are known as W+, W-, and Z0.

Philip C. Habib, the special American envoy, began trying today to resolve what were described as relatively minor differences blocking a final agreement on evacuating Palestinian guerrillas from west Beirut. Mr. Habib returned here from Jerusalem and briefed Prime Minister Shafik al-Wazzan of Lebanon on the latest Israeli concessions in the negotiations. The Prime Minister told reporters that he expected the remaining issues to be resolved shortly and ''implementation'' of the Palestine Liberation Organization withdrawal to begin this weekend at the latest. Mr. Wazzan said that ''differences have now narrowed to the point where they have almost disappeared.'' (In Jerusalem, a ranking Government official said the return of an Israeli pilot and the bodies of nine soldiers was the only issue that remained unresolved, adding, ''All other obstacles have been swept away.'' Page A16.)