The 10,000 Secrets of the Circus : SPANGLE <i> by Gary Jennings (Atheneum: $21.95; 704 pp.) </i>

Gary Jennings first made a name for himself in American fiction with “Aztec,” a highly imaginative account of the conquest of Mexico as seen from the Aztec side. He followed this with “The Journeyer,” a similarly inventive and heavily researched novel about Marco Polo’s travels to the Orient. These are essentially fictional exercises in the far away and long ago, somewhat in the manner of Mary Renault’s “The King Must Die” and her other re-creations of the classic world.

But unlike Mary Renault, Jennings does not take advantage of acquired momentum and never writes twice about the same thing. “Spangle,” the history of a circus traveling across America and Europe in the years following the Civil War, is his first attempt to use a setting in a relatively modern period and deal with people who are something like us, who think as we do, wear clothes something like ours and talk more or less as we do. The distance of 120 years lends a certain note of the odd and different, but essentially this is a realistic novel, not a romance. This causes Jennings to stumble now and then, but it is also the great strength of “Spangle” and its superiority over his first two books.

When we first catch sight of Florian’s Flourishing Florilegium of Wonders, it’s a run-down traveling circus in the backwoods of Virginia, with one elephant and an undernourished lion, owned by the international entrepreneur Florian. After the surrender at Appomattox, Florian is joined by a pair of demobilized Confederate soldiers. One of them is cavalry officer Zachary Edge, who becomes an exhibition sharpshooter and Florian’s lieutenant.

The circus travels across Virginia and West Virginia, then embarks for Europe on a collier. Along the way it picks up performers and amateurs it can train, as a rolling snowball picks up snow, even robbing the ship’s crew of its engineer and sailmaker. In Europe, after initial hardships and setbacks, the circus catches the public’s fancy and becomes a success, partly because of its American “exoticism” and European sympathy for the Confederate cause, factors shrewdly played on by Florian.

There are visits to Rome, Florence and Vienna. There is a command performance before the Austrian court, a ball at the palace of Czar Alexander in Petersburg and a meeting with Napoleon III in Paris, during which Edge gives the emperor advice on how to conduct his war against the Prussians to no avail--the Prussians win anyhow, and the show goes on under the bombardment of Paris during the Commune. The novel comes to a close as Florian dies of a stroke, to the trumpeting and roaring of his grief-stricken animals, and Edge ends up in the arms of Sunday, the last of the numerous female performers he romances during the story.

So much for the bare outlines, which cannot do justice to such a long, dense and heavily documented book. Jennings knows a great deal about circuses and loves to pass it on. “Spangle” sets out not only to tell a story but to convey the 10,000 pieces of information he acquired in the course of his research (he traveled with nine circuses in America and Europe). It includes a virtual operator’s manual on how to erect a Big Top; we learn that all circus elephants are females but are called bulls, and there is endless information on such things as how counterfeiters were flogged in Czarist Russia, how to load and fire period firearms, how circus performers keep their genitalia from showing through their tights, how to make a pig climb a ladder, and how to make a Fat Lady out of an ordinary colored cook. (There is a lot of racist terminology.) Jennings is obviously an enthusiast on his subject, and his enthusiasm is contagious. Before the novel is over we develop, along with the characters, a contempt for non-circus people and a conviction that the only sensible and reasonable thing to do in this wayward world of ours is to run away and join a circus.

It’s easy to find faults. Jennings is not an elegant stylist, and if you didn’t like “Aztec” you will probably dislike “Spangle” for the same reasons; it’s heavy-handed, the eroticism is clumsy and often embarrassing, the dialogue is unconvincing, the violence is gratuitous, and the attempts at narrative excitement tend to be of the old “suddenly a shot rang out” variety. There are constant attempts at humor, but they seem to be intended for mental defectives; Jennings works like the old vaudeville comedians who first told you they were going to tell you a joke, then they told you the joke, then they told you they had told you a joke, then you laughed. “Spangle” is not agile, lithe and economical. It is not a slick minimalist novel. It is not by Donald Barthelme or John Updike.

In the end, none of this matters very much. If you like it, you think it’s epic, finely wrought, erudite, richly comic, delightfully bawdy and highly dramatic. “Spangle” is impressive in its sheer mass and richness, in the enthusiasm and energy of its telling, in the obvious pleasure the author takes in his work. We have to remind ourselves that a book more than 700 pages long can’t be as finely honed as Voltaire’s “Candide,” that Milton is full of long, dull passages, and that even Homer nods. “Spangle” starts off well enough, but as the circus acquires more entertainers, acts and animals in Italy and Austria, the story begins to get lost in the masses of detail. The watershed for many readers will be the way foreign languages are handled. Jennings treats us to a goulash of dialogue fragments, terms, and expressions including French, Spanish, Dutch, Italian, German, and Magyar. Impressive, but could an aerialist named Levy change his name to LeVie? Not if you know that vie is a feminine noun.

But it does make us want to run away and join the circus. A typical passage--so striking you can’t get it out of your mind--occurs early in the novel, when the circus is still in America. Edge, taking a walk outside the Big Top at night, finds the circus’ sole elephant posturing in the darkness, setting one foot and then another on a tent stake, sitting on her rump and waggling her front legs. It is some time before he realizes what she is doing. She is rehearsing her act for the next day.