JOHN OSBORNE, who died the other day at the age of 74, was a reporter whose work set an enviable standard of accuracy and fairness for others in the profession. Mr. Osborne's career divided into two phases: the first included nearly a quarter-century from 1938 to 1961 spent mainly as a reporter and editor for Henry Luce's Time, after which he resigned to begin a seven-year period in Washignton's free-lance wilderness.

The second phase of what he himself once described as a "long, up-and-down-and-up career in journalism, mostly for The Establishment," began in 1968, when Mr. Osborne begans his "Nixon Watch" column for The New Republic. Within a short time, he had emerged as an unparalleled weekly chronicler of the Nixon presidency: meticulous in his research, alert to his own errors and prompt to correct them, restrained and reliable in his judgements of people and policies. A remarkable number of Mr. Osborne's dispatches stood the retrospective test of compilation, six book-length chronicles in all, which turned him into a latter-day Tacitus of the imperial presidency at its height -- writing on the Nixon White House as his Roman prodecessor had done on a series of emperors, "without either anger or zealousness."

Although sometimes chided by colleagues and readers for an excessively sympathetic view of White House behavior, Mr. Osborne made no apology for his willingness to write from "a controlling respect for the presidency as an institution that generally exceeded respect for the man." He struggled to maintain that respect, despite the periodic mood swings by the public and press, througout the Nixon, Ford and Carter presidencies. Often, his own profession irritated him more than the one he watched so assiduously.

Mr. Osborne brought an admirable measure of patience and courtesy to the task of covering politics and government. "I should note that in 47 years of reporting, I never thought that public officials were obligated to give me their time and confidence," he wrote in a rare confessional statement occasioned in late 1974 by President Nixon's resignation earlier that year. "I have considered that it's been my job to persuade them to do that." The polite persuasiveness of John Osborne will be missed sorely by his many friends and admirers on the "Reagan Watch" ahead.