NOT SINCE J.R.R. TOLKIEN'S "Lord of the Rings” hit it big in the '60s have juvenile fantasy novels struck a chord with American grown-ups the way the Harry Potter books are doing. That's not because the genre hasn't offered stories as fanciful and gripping. Diana Wynne Jones' "Chrestomanci” novels, Susan Cooper's "Dark Is Rising” sequence and Philip Pullman's "Sally Lockhart” and "His Dark Materials” trilogies all spring to mind -- not to mention Ursula K. Le Guin's "Earthsea” tetralogy. (Anyone still hungry after devouring all 734 pages of the latest Potter might want to give some of these a whirl.)

But until Harry Potter, it was almost impossible to convince adults to read such mere fairy tales. Now they're clamoring for the stuff so forcefully that to satisfy them, booksellers stayed up long past their bedtimes Friday night, when the fourth book went on sale.

It's impossible to say for certain why. My guess is a combination of the same sort of mathematically determined forces that make chaotic water molecules snap into a snowflake's orderly crystal or make individual pigeons wheel together in a flock; timing, now that the sons and daughters of Tolkien- fed baby boomers have reached reading age; and dumb luck.

J.K. Rowling, after all, writes very much in the tradition of Tolkien and his buddies T.H. White and C.S. Lewis, authors of (respectively) "The Once and Future King” and "The Chronicles of Narnia.” Like that august trio, she bundles together a comforting British coziness with an urgent moral battle over the fate of the world. (That's also a traditional British theme -- think "Paradise Lost.”) She throws in a perfect understanding of the joys of repetition, as well. In the first Harry Potter book she set up a pattern -- opening chapters spent with the orphaned hero's horrible relatives, a magical trip to the Hogwarts School of Witchcraft and Wizardry where he's a student, schoolroom scenes with mismanaged potions and magical creatures run amok, intramural rivalries, a Christmas feast and so on. You can count on her to repeat these scenes in each book -- with a twist.

In "Harry Potter and the Goblet of Fire,” she gives us the satisfyingly familiar, bumped up a notch. The three previous books turned on Quidditch matches. A sport played on flying broomsticks with three kinds of magical balls, Quidditch inspires the same passion among witches and wizards that soccer does among Muggles, or nonmagical people. In the earlier books, competition among the four Hogwarts Houses for the school Quidditch cup allowed Harry to show his stuff. Although marked on the forehead with a lightning-shaped scar from a curse that killed his parents, Harry is an ordinary boy in most respects -- except when it comes to Quidditch, where he's a demon on a broom. In "Goblet of Fire,” however, Rowling goes beyond varsity. She takes us to the Quidditch World Cup, where events surrounding the match between Ireland and Bulgaria threaten world-shattering consequences. Similarly, the scholastic rivalry among the four Hogwarts Houses gives way in "Goblet of Fire” to the Triwizard Tournament, in which

students from Hogwarts and two foreign schools match skills as they battle dragons and other dangers.

Harry and his friends are 14 this year, so adolescence looms. Harry does a lot of blushing and pining over lovely Cho Chang, whom we met last book on an opposing Quidditch team. His scholarly friend Hermione garners three invitations to the Christmas dance, despite her buck teeth. Even Hagrid, the gigantic gamekeeper and Care of Magical Creatures teacher with a weakness for slime and fangs, finds a suitably vast lady to admire.

Readers love Rowling's characters. Along with old favorites such as Professor Dumbledore, the wise, gray-bearded headmaster, and hot-tempered, hyperrational Hermione, Rowling introduces many delightful new ones. Every year brings a new Defense Against the Dark Arts teacher; this time it's Mad-Eye Moody, whose face "looked as if it had been carved out of weathered wood by someone who had only the vaguest idea of what human faces are supposed to look like, and was none too skilled with a chisel.” He also sports a wooden leg with a clawed foot and one magic eye that can see through walls -- as well as the back of his head. Perhaps in response to her unprecedented fame, Rowling introduces a pushy journalist, Rita Skeeter, who writes wonderful parodies of tabloid scandalmongering for the wizard press.

At two and a half pounds (I weighed it), "Goblet” allows plenty of scope for Rowling's signature whimsy. There's the grandfather clock in the living room of Harry's best friend, Ron Weasley, for instance: "It was completely useless if you wanted to know the time, but otherwise very informative. It had nine golden hands, and each of them was engraved with one of the Weasley family's names. There were no numerals around the face, but descriptions of where each family member might be. ‘Home,' ‘school,' and ‘work' were there, but there was also ‘traveling,' ‘lost,' ‘hospital,' ‘prison,' and, in the position where the number twelve would be on a normal clock, ‘mortal peril.'”

The sheer weight of the book makes it sag somewhat in the middle. There's a little too much coziness between the first chapter, when we see Harry's nemesis, Voldemort, the Dark wizard who killed the Potter parents, boast about his plans to do Harry in, and the book's last fifth or so, when the Dark-force action heats up again. Should Rowling have made cuts? Perhaps.

But what? The scene where Hermione tricks the school nurse into shrinking her teeth? The one where she teaches the Bulgarian Quidditch hero to pronounce her name? The beautifully proportioned room full of chamber pots that Dumbledore stumbles on? Thanks, I'll keep them all.

Polly Shulman is Newsday's Sunday book critic.

Newsday (Jul 10, 2000)