That first test, 40 years ago in New Mexico, has been described poetically by the inventors of the nuclear bomb, some of whom are sorry now. Subsequent tests, on Pacific islands and in American deserts, evoked no poetry, but some bewildered servicemen have lived with the consequences ever since.

Representatives of two Trinity alumni groups were on Capitol Hill for the anniversary of Trinity, as the first explosion was named by J. Robert Oppenheimer. Trinity scientists Victor Weisskopf, Robert Bacher, Hans Bethe, Philip Morrison and Cyril Smith held, under the auspices of the Union of Concerned Scientists, a somber seminar in the Senate auditorium, during which they pleaded for a reduction of a stockpile to which they made the first fateful contribution.

At the same time, a House Veterans Affairs subcommittee listened to the pathetic testimony of atomic veterans, those good soliders and sailors who marched or sailed into the heart of the fallout caused by the 235 tests carried out during the halcyon days when scientists unaccountably failed to warn the authorities of radiation hazards.

The atomic veterans, who cheerfully scrubbed the decks of vessels used in the tests or played in radioactive waters, certainly did not know. One of them, Robert Farmer, then a 19-year-old seaman, stepped ashore on Bikini Island hours after two 23-kiloton bombs had been exploded. After eight of his nine children were born with serious genetic defects, he began to make the connection.

Farmer suffered from cancer of the thyroid and heart problems. The Veterans Administration, which hates to consider ills imposed on servicemen by their own side, had no time for him. He got the treatment later accorded to Vietnam veterans zapped by Agent Orange. Finally, Farmer went to then-Rep. Paul Simon (D-Ill.), a man with an acute sense of justice. Now a senator, Simon has drafted a bill that clearly establishes the government's responsibility to the forgotten victims.

To the unexpectedly sympathetic subcommittee, Simon explained his proposal for relief for atomic veterans. To begin with, he wants to have their radiation-related ailments treated as service-connected disorders. In the long run, Simon calls for the establishment of a program of research and training for servicemen exposed to radiation.

The Reagan administration is flatly opposed to the Simon solution. VA General Counsel Donald L. Ivers denounced it as a wicked extravagance. He claimed the cost would be an alarming $23 billion. He arrived at this figure by including all atomic-era veterans in the possible clientele.

Simon says he is concerned only with the 250,000 servicemen who participated in the 235 tests so blithely carried out by the authorities between 1946 and 1962, before the Kennedy test ban.

Presently, the burden of proof that an illness, often long years after exposure, is caused by radiation is on the veteran. Records of participation are apparently sketchy. For instance, Ford Harrison, a 71-year-old Navy veteran from Selma, Ala., testified that he was part of a landing force at Nagasaki 33 days after the second of two explosions that ushered in the era of nuclear weaponry. He stayed there two weeks. Five months later, his teeth fell out. Since then, he has suffered from lung cancer and skin cancer. The Veterans Administration denied his claims because they said he could not prove he was in Nagasaki. But he could, with pictures.

Simon pointed out while the administration is fighting him on relief for atomic veterans, the Department of Defense is pushing a bill that contains a trust fund for claims of victims of low-level radiation in the Marshall Islands, where many of the 66 South Pacific tests were conducted.

The stricken scientists who are now pleading for the lives of potential nuclear casualties might do well to lend an expert hand to these actual, unintended victims of their genius. The lack of information that led the services to expose 250,000 uniformed Americans to radiation still afflicts the atomic veterans, who are expected by their government to provide "scientific" evidence that radiation is the cause of their woes. Who could help them better than the scientists, whose ignorance -- or indifference -- informed the 20-year orgy of testing?

No one wants to add to the regret and guilt of these distinguished scientists, who were looking for a weapon to end World War II and found one that could end the planet. But they are plainly seeking atonement. The atomic veterans offer them a most appropriate form.