The Wave, by Evelyn Scott (Carroll & Graf, $9.95). In 1929 when this novel of the American Civil War was published, it was acclaimed (by Clifton Fadiman and Joseph Wood Krutch, among others) as the Civil War novel. Contemporary readers may find its episodic style annoying, but there is no doubt that its sheer bulk (625 pages) and narrative power (Sumter to Appomattox, Ford's Theatre to the federal victory parade down Pennsylvania Avenue) demonstrate a powerful intelligence is at work.

Easy in the Islands, by Bob Shacochis (Penguin, $5.95). Bizarre, often absurd, funny and poignant. Such are the stories in Bob Shacochis' recent winner of the American Book Award for first fiction. Most of the tales concern Americans, at varying stages of disaffection with life, who've arrived in the Caribbean looking for escape or revitalization, or just merely a change. What most of them find is a kind of confusion where nothing is ever as it seems. NONFICTION

Losing Ground: American Social Policy 1950- 1980, by Charles Murray (Basic Books, $10.95). This thoughtful, controversial book argues that the social programs of Lyndon Johnson's Great Society have not helped the working-aged poor and disadvantaged and in some cases have even made their condition worse. The argument is buttressed by an extraordinary amount of statistical data. Whether one agrees with the author's conclusion or not, any discussion of future social policy will have to take his evidence into account.

The Living History Sourcebook, by Jay Anderson (American Association for State and Local History, 172 Second Avenue North, Nashville, Tenn. 37201, $19.95 plus $1.50 postage). "Living History" is simulated history, history by doing, as for instance Colonial Pennsylvania Plantation, a replica 1770s farm just outside Philadelphia, or the reenactments of Civil War engagements which attract so many. Colonial Williamsburg is living history at its most elaborate, but it can be much simpler, or more playful, as in the many board games that recreate historical events. This guide has 360 entries to living history resources, including museums, events, magazines, books, articles, organizations, suppliers, sketchbooks, games and films.

Time's Arrows by Richard Morris (Touchstone, $8.95). Both the first and last chapters of this book are entitled "What Is Time?" which suggests that one may read the intervening material without any time lapsing. In this literate account for the lay reader, physicist Richard Morris tries to grab hold of that quicksilver abstraction which Tennessee Williams called "the enemy of us all." Morris' remark that "Sometimes it seems that scientific investigations into the nature of time reveal more about what time is not than they do about what time is" should not put readers off. Along the way to his non-ending (an objective correlative of time's openendedness), he encapsulates human thinking and experimenting about time instructively and with style. One conclusion he does arrive at is the age of the universe: between 7 and 20 billion years old. (Admittedly, there is an enormous gap between those two figures, but what difference could it make to you and me?) FANTASY AND SCIENCE FICTION

Mermaids, edited by Jack Dann and Gardner Dozois (Ace, $2.95); Barbarians, edited by Robert Adams, Martin H. Greenberg and Charles G. Waugh (Signet, $3.95). Sometimes, it seems, mermaids and barbarians define the whole realm of fantasy -- romantic faery and flashing swords. In the latest Dann-Dozois collection (their previous editorial collaboration produced Magicats), readers are treated to a delightful historyf mermaids (by that wonderful writer, Avram Davidson), followed by stories from Gene Wolfe, Samuel Delany ("Driftglass"), Theodore Sturgeon ("A Touch of Strange"), Jane Yolen, Pat Murphy, Lewis Shiner and others. In Barbarians Robert Adams (creator of the Horseclans series) rounds up an equally imaginative blend of the old and the new: a Robert E. Howard novella about Conan ("Beyond the Black River"); a Kane story by Karl Edward Wagner; and "Scylla's Daughter," one of Fritz Leiber's Fafhrd and Gray Mouser classics. Other writers represented include Poul Anderson, Larry Niven, Andre Norton, and George Alec Effinger, this last by the preppy- heroic fantasy, "Maureen Birnbaum, Barbarian Swordsperson."

Nebula Awards 20, edited by George Zebrowski (Harcourt Brace Jovanovich, $8.95; cloth, $17.95); Isaac Asimov Presents the Great Sf Stories 14 (1952), edited by Isaac Asimov and Martin H. Greenberg (DAW, $3.50). Each year the Science Fiction Writers of America give Nebula awards to the best fiction of the year; this anthology gathers the winning titles for 1984, including John Varley's horror novella "PRESS ENTER," Octavia E. Butler's story of human-alien symbiosis, "Bloodchild," and Gardner Dozois' "Morning Child." As the award-winning novel, Neuromancer, could not be included, William Gibson is represented by "New Rose Hotel." Other features of this collection: runner-up stories by Gene Wolfe, Michael Bishop, and Kim Stanley Robinson, a pair of sf poems, and essays on the year's books and movies by Algis Budrys and Bill Warren, respectively. The Asimov anthology series, working from the late 1930s, gathers the best stories of each year; in 1952 memorable -- indeed unforgettable -- work included Ray Bradbury's "The Pedestrian" and "A Sound of Thunder," Alfred Bester's pyrotechnic "Hobson's Choice," and one of Isaac Asimov's finest short works, "The Martian Way."

The John W. Campbell Letters, Volume I, edited by Perry A Chapdelaine, Sr., Tony Chapdelaine, and George Hay (AC Projects, Rt. 4, Box 137, Franklin, Tenn., 37064, $5.95; cloth, $35). A good case can be made -- and in fact has been -- that John Campbell is the most important figure in the history of modern American science fiction. As the editor of Astounding Campbell exercised immense influence over the careers of such writers as Robert Heinlein, Isaac Asimov, A.E. van Vogt and dozens of others, suggesting plots, acting as father-confessor, encouraging, hectoring, and proselytizing. As a writer, he was almost equally important; as Don A. Stuart he gave the world "Who Goes There?" (later the basis for the classic horror film The Thing) and that elegiac vision of the end of man, "Twilight." The letters gathered here act as a time capsule, taking readers into the world of 1940s and 1950s pulp fiction, providing gossip about notable sf prfessionals, and offering a self- portrait of a cranky yet fascinating man.