Sometimes you get the feeling that there are almost as many ways to study history as there are historians.

One way is to study the historians themselves.

At least 2,500 of them were in town this week for the 97th annual meeting of the American Historical Association (AHA), and they talked about everything from the changing views of saints in the 11th to 13th centuries to the fate of the Equal Rights Amendment (ERA).

There were 111 separate sessions during the three days, and each one had its own rather characteristic audience. Take "Cultural Fallout: The Bomb in American Life." An intense group this, more than 100 people and growing all through the afternoon. Beards and shirtsleeves. And a lot of women, possibly because Elaine Tyler May, of the University of Minnesota, was discussing "Sex, Women and the Bomb."

One interesting point she made: The establishment's belief that housewives would be a vital stabilizing factor after a nuclear war may have led it to question and even attack women's sexual and economic liberation--women had to be contained, along with the Soviets. Sexual emancipation somehow would lead to race suicide, and so on. Significantly, May noted that Phyllis Schlafly started out as a cold warrior.

This audience kept busy passing mailing lists and resolutions to sign. They learned that the AHA was working on a nuclear freeze resolution--which later was adopted. They applauded Wisconsin professor Paul Boyer's analysis of the curious disappearance of the antibomb movement from 1963 to the mid-'70s.

He cited "the illusion of diminished risk," the reduction of fallout fears when the testing went underground, the emergence of "atoms for peace," deterrence theory which intellectualized the issue and new causes such as Vietnam which diverted attention.

Even SANE (The National Committee for a SANE Nuclear Policy) dropped the word "nuclear" from its rubric in 1969, he said, though today "it seems to have reappeared."

Just next door a very different roomful of historians was hearing about presidents and the press from Roosevelt through Eisenhower. A smaller group, it seemed more relaxed, quicker with the funny questions. There was a smell of cigar smoke.

The speakers were pretty relaxed, too. Old Washington news hands like Chalmers Roberts and Robert J. Donovan told Ike stories and discussed television journalism with a certain caution, lest a TV commentator drift into the room. History here was the story of national leaders and the people around them, a fairly traditional approach.

A newer approach--history through statistics--drew yet another kind of audience yesterday for discussions of "Right-radical Youth in Germany, 1918-82." These were sober people, soberly dressed, who paid almost fanatically close attention, appeared to have read every abstruse book the speakers mentioned and took notes in tiny handwriting.

Michael H. Kater of York University in England, one of 10 foreign countries represented, examined in remarkable detail the shifts in average age of Nazi party members in the early Hitler years. The extreme youth of those members--over half of the SA (Sturm Abteilung), the first storm troopers, were younger than 25--was almost matched by the youth of their officers.

Unemployment was a major reason for their joining the party, he said, that and resentment of the older generation of Germans for getting the country into such a chaotic state after World War I. They liked the Nazis for their "activism in support of their principles" (that is, street fighting) and their rejection of intellectualism.

Working with a wealth of meticulous German records, Kater was able to analyze the early party makeup: small-town blue-collar youths, many unemployed; lower middle--class people, particularly peasants, minor civil servants and female clerks (average age 30); university students from the elite classes.

In contrast with this overload of source material, Medieval historians have slim pickings indeed. Searching for the relationship of epidemics and social change in 14th- and 15th-century Italy, Ann Carmichael of Indiana University had to work mostly with fragmentary burial records from various towns.

The great fear of that era was the Black Plague, and sometimes it seems other diseases were mistaken for it. Thus, those "pestilential pustules" people were forever talking about could have been smallpox or some other disease and not plague at all.

When two districts in Florence show a rash of smallpox deaths, the question arises whether this was simply because the gravediggers in those districts--who turned in the burial reports and apparently are our source for cause of death--happened to recognize smallpox, while their colleagues just wrote it off as plague.

Carmichael also observed that towns which quarantined disease victims usually were late in developing lazaretti, or pesthouses, and that the rich often were slow to act against diseases which attacked mainly the poor.

This audience was quite young, for as the University of Maryland's John Duffy pointed out, the study of health and disease as factors in history is a relatively new idea for historians.

A somewhat livelier historical method was described by Ronald G. Witt of Duke University, who has his graduate students re-enact famous confrontations from the past. He showed a tape examining Pope Gregory VII's excommunication of Henry IV, the Holy Roman emperor, with costumed students marshaling their arguments from contemporary documents.

Only certain events, such as trials, can be treated this way, he said, but it shows students how malleable history is, and it does get them into the libraries.

And not far away, still another audience of historians (gray-haired, tweedy, pipe-smoking) watched World War II newsreels and saw what could be done with aerial photos to help us understand the past.

There were films ("The ERA in Illinois") and a whole roomful of books for sale, and one immense chamber at the Sheraton Washington was devoted to job-hunting. This interesting exhibit featured lists of openings by area of expertise and even gave details about job interviews. The audience here was the most deeply attentive of all.