BOOK REVIEW : Some Essays Are Just Better Off Forgotten : BALANCING ACTS: Essays <i> by Edward Hoagland</i> ; Simon & Schuster; $23; 351 pages

The essayist’s lot is not a happy one these days. True, essays have become more common in recent years; true, the work of our best essayists eventually turns up in book form, as this decade’s-worth of articles from Edward Hoagland attests.

But look at the periodicals in which the 25 pieces in “Balancing Acts� were originally published, and you’ll see that Hoagland--whom John Updike has called, as the dust jacket trumpets, “the best essayist of my generation�--has been turning up in some fairly unlikely places. There’s Harper’s, Esquire and the New York Times Book Review, of course, but also House and Garden, Outside and Interview--not the sort of publications generally associated with distinguished, literate reflection.

That the thoughtful essayist can write for such a diverse array of magazines is no doubt a good thing, but it’s also indicative of the fact that essayists today are pens for hire, caught up in the business of writing as much as in writing itself.

That duality is apparent in “Balancing Acts,� or is at least one possible explanation for its unevenness. Many of the pieces--Hoagland’s eulogy for fellow writer Edward Abbey, his appreciations of Muir and Thoreau--are fine, but others are uncharacteristically prosaic. Hoagland could just as well have been describing himself in his best work when he writes that Abbey “had about him an authenticity that springs from the page,� but in “Balancing Acts� that authenticity is only intermittent.

When Hoagland writes in abstract terms--on the lack of moral force in modern writing, the “velocity� of life in the United States--his prose feels unanchored, unfinished, as if the subject were assigned to him and proved less than congenial. For example, “Learning to Eat Soup,� apparently verbatim extracts from a notebook first published in Antaeus, is an embarrassment.

But enough criticism. It’s not exactly fair to hold Hoagland to higher standards than other essayists just because he met such standards in the past, indeed helped set them. On the positive side, a number of pieces in “Balancing Acts� are vintage Hoagland and demonstrate that his range transcends that of the typical “nature writer.� (That is a characterization, incidentally, Hoagland can’t abide, although his most eloquent work seems to involve nature and the environment.)

In “Up the Black to Chalkyitsik,� he introduces us to Ft. Yukon (record low, 78 degrees Fahrenheit below zero; record high, 105 degrees Fahrenheit) where the rivers can be so silty that capsized fisherman are dragged down not by water, but by sand collecting in their clothes. In “West on the Zephyr,� an account of transcontinental railway travel, he notes wisely that “with age, we become responsible for what’s in our heads.�

At the end of “In Okefenokee,� we come across a bib-overalled Georgian, who says there used to be so many fish in the swamp “you had to hide from them to put your bait on.� And early in “Arabia Felix�--one of Hoagland’s finest travel essays, intertwining the history, politics and geography of Yemen with observations of natives and fellow tourists--we meet a hitchhiker with a hand grenade. He is returning home to “help with the killing,� the hitchhiker says, his own village being at war with the neighboring town.

These four articles--plus the essays on Muir, Thoreau and Abbey--amount to more than 180 pages. That’s virtually a book right there, and it makes one wish that “Balancing Acts� had been limited to these and a few other worthy pieces.

There should always be room in the world for a writer’s “occasional� work, to be sure, but very little of it merits preservation between hard covers. Hoagland tarnishes his image when he republishes lesser work, just as the goose appears rather less magical, and more fit for the table, the moment it begins to lay bronze eggs rather than gold.