An obscure government report certifies the departure of a dazzling period in American intellectual life -- the long, postwar era of jet-set professordom.

Sure, some of them still log more time aloft than behind the lectern. And a few persist in believing that a truly meritorious scholar not only should spend most of his time as a visiting professor someplace else, but also should, as often as possible, be away from that other place as a guest lecturer at still another place.

The male gender is used knowingly here because, with occasional exceptions, few women were admitted to this circuit until just recently -- which, by unfortunate coincidence, was when the economics of academe went sour. w

The turned situation can be seen in the above-mentioned report, Science Indicators -- 1978, an assemblage of vital statistics and commentary on the state of American science, newly published by the National Science Foundation. There, in Table 1-30 on page 169, is the evidence:

The 42 international scientific congresses held in 1966-68 drew 12,297 American participants; the 52 international congresss held in 1975-77 drew 12,767 American participants. Thus, nearly 10 years later -- during which time the ranks of American science and engineering experienced a net gain of about 100,000 people -- and with 10 more congresses, total U.S. attendance was virtually unchanged.

For specialists in the pathology of learned institutions, these seemingly bland statistics are rich with meaning because travel money is the last discretionary money to be clamped down on when times get tough. And when American scientists aren't mantaining a strong airborne presence, we are at last upon firm evidence that the fat has been sweated out of the system. $ what has to be understood about modern academe and its various non-profit institutional outcroppings is that expense-paid travel is their counterpart of the business world's expense-paid lunch. In fact, subsidized travel is one of the very few special sweteners that career academics can expect in a profession that, for reasons fo need, tradition and public relations, tends to be skimpy with extras for its rank and file.

Travel, not just to the superbowl meetings -- formally called congresses -- but also to the many more small and specialized meetings, most often is underpinned by a sound professional reason: to read and hear papers and to meet with faraway colleagues. But, as all veterans of the conference business know, the volume of attendance is closely lined to the charm of locality. thus, even dull meetings on the Adriatic Coast invariably are swamped, and facilities must be booked years in advance.

Professors sometimes are embarrassed by the geographical convergence of work and play and will say that the conference organizers ought to pay more attention to nearby meeting places than to the touristy spots. Medical doctors, however, being richer than university professors and more experienced in the good life, long ago shed any squeamishness about professional get-togethers in holiday circumstances. Regularly appearing in medical journals are explanations of how -- in accordance with IRS requirements -- forthcoming meetings at some comfy watering place can, in large part, be written off as business expenses.

That method, however, won't transplant to academe, where one of the bedrock tenets of professordom is that you can't amount to much if you have to pay for your own tickets.