The idea of Washington as a foreign country -- a place with its own customs, rituals and language -- sounds peculiar only on this side of the Potomac. To the rest of the nation, it's self-evident. Americans can't be blamed for sometimes thinking of their government as one big Aztec sacrificial rite.

So there's something natural -- even necessary -- about using an anthropological lens to view the most ritualistic and idiosyncratic institution of all: the U.S. Congress. J. McIver Weatherford is a former legislative assistant (to Sen. John Glenn D-Ohio ) and an anthropology PhD. His aim is to use the latter skill to temper his insider's analysis of Congress with the sense of detachment that is the anthropologist's stock in trade.

Weatherford travels a long way in this informative, imaginative, though often overwrought book -- all the way from the Indians who first settled this part of the country (then known as Nacochtanke) through Daniel Webster, senator and bank lobbyist, to the disruptive parliamentary tactics of what he calls the "Terrible H's" (Sens. Helms, Hatch, Hayakawa, Humphrey and Hawkins). While he has the good sense to avoid the jargon of both of his professions, he can't seem to decide whether the anthropology angle is a pop gimmick designed to make the study of congressional folkways more palatable, or a serious attempt at cross-cultural analysis.

His gimmicks are diverting, if insubstantial. Congressmen find themselves divided into handy categories. "Shamans" are the charismatic witch doctors who put on a good show for the cameras but don't usually accomplish much. (Ted Kennedy and Larry Pressler are examples.) "Warlords" are the domineering committee chairmen with a stranglehold on particular issues (John Stennis, Mark Hatfield). "Godfathers" are the party leaders who can occasionally unite many tribes under one banner (Sam Rayburn, Howard Baker). Congressmen, we're told, "approach the lobbies like Persian satraps collecting tribute from their subjects." The powerful members spend their days just as the "Big Man" warriors of New Guinea do -- dividing up pork.

All of this is fun enough, if not entirely accurate (many lobbyists cannot exactly Book World TRIBES ON THE HILL. By J. McIver Weatherford. (Rawson, Wade. 300 pp. $13.95) be characterized as "subjects"). Where Weatherford gets in trouble is in dislodging his tongue from his cheek and taking the anthropological analogies seriously. "Despite the discontinuity in appearance between the three-piece-suit politicians in Washington and the tall, feathered Watusi warriors, a lesson can be found in examining their political life -- a lesson that is all too easily missed when we succumb to a myopic examination of our own institutions," Weatherford writes. After that particular drumroll, the earthshaking "lesson" learned is that congressional tribesmen, like their Watusi brethren, also struggle for turf and domination over rivals. Such profoundity could land him in the Congressional Record some day.

Weatherford's approach to Congress is much more revealing when he uses the tools of anthropology -- identification of rituals, relationships and functions -- instead of comparisons to other cultures. Thus his description of how the "Watergate Babies" elected in 1974 stopped attacking the seniority system once they started benefiting from it is more insightful (if less outrageous) than, say, his comparison between the Longworth House Office Building and a Shavante Indian bachelor hut. Similarly, his analysis of how the power of "congressional clans" dependent on the size of their staffs is more compelling than his efforts to liken Hill staffers to courtiers at Versailles. Throughout, colorful cultures work better as metaphors than as rigid models.

There are some factual errors here (John F. Kennedy never served on the McCarthy Committee), and Weatherford has an exaggerated sense of Congress' power in relation to the executive branch. He forgets that legislators don't have much of a club to hold over tenured bureaucrats, and that making laws is very different from implementing them. While suggesting that congressmen expand their influence by placing former staffers in strategic points throughout the government, he neglects to point out that survival networks usually develop with more subtlety than that -- through informal social connections and exchange of favors.

But Weatherford's larger point remains on target. Ceremony and custom do often dominate congressional life at the expense of substance, and an effective president knows how to use that to his advantage. It was clear from the moment he denied Tip O'Neill extra inaugural tickets in 1977 that Jimmy Carter didn't understand the importance of respecting congressional custom and wouldn't do well with Congress -- regardless of what his proposals contained. Ronald Reagan, of course, understands these rituals, and up to now he has exploited the values and vanities of posturing congressmen with skill. Call them icons or anything else, but those presidential cufflinks mean something to the tribes on the Hill.