‘Round Midnight : A DAY IN THE NIGHT OF AMERICA, By Kevin Coyne (Random House: $22.; 316 pp.)

This is the ultimate travel book. Kevin Coyne, our guide and companion, is not primarily interested in exploring areas of land (though he zigzagged 18,028 miles through 43 states to do this book) but in exploring a portion of time itself. The clock is his globe, and night--which he says “remains a largely unfamiliar province, probably as well known as, say, Montana was in the first part of this century”--is the particular portion of the clock he takes us through.

Some of the things he has to say about it will not, of course, be news to the 29 million Americans who typically are still awake just after midnight or the 10 million “colonists” still propping their eyes open around 3 to 5 a.m., “the lowest ebb of national consciousness.”

Not only are most of these folks awake, they’re working, and Coyne has gone around visiting them on their jobs--cops, nurses, steel and glass workers, street repairmen, fishermen, reporters, immigration officers, bakers, and many etceteras. He believes the character of night is shaped by workers, not by players or criminals or lovers--though this point, of course, is arguable.

The U.S. Census Bureau declared the frontier settled in the 1880s, but in that same decade, Coyne reminds us, the age of electricity began, triggering the equivalent of an Oklahoma land rush. The new frontier was night, then still largely uninhabited. World War II’s round-the-clock factory schedule accelerated the industrial rhythm of the nation, and today, says Coyne, about one of five American workers is on “something other than the standard daytime schedule, whether evenings or nights or rotating shifts.”

Travel books seem to establish an especially close relationship between the writer and the reader, and the latter quickly learns if he is going to be stuck with a boring guide. This time, we’re in luck. Coyne, whom Random House identifies only as “a journalist living in Freehold, New Jersey,” is almost always an enthusiastic, imaginative fellow, and his writing is usually crisp and elegant.

But he can be irritating. First of all, he suffers from The-Common-Man-Is-Wonderful pox, a disease that leaves its victims oblivious to the fact that ordinary people, even those in extraordinary jobs, can be dull as dishwater and the things they say--unless processed through some genius interviewer like Studs Terkel--are usually painfully trite.

Second, Coyne sometimes really gets bogged down in details. Why didn’t some Random House editor suggest (after all, this is his first book and he could use a few suggestions) that his readers might not want to put up with an account of what seems to be every single item sold in a 7-Eleven, or wade through an excruciating eight-page recapitulation of a Tampa talk-show hostess’ conversations with a variety of dimwits?

I hasten to add that Coyne’s love of details usually serves very well as a kind of pointillist development of his big, sparkling picture of night life.

Night workers (we are told), because they tinker with their biological clock, lose an average of a full night’s sleep each week. . . . Don’t regret the five years of your life you spend dreaming, for those dreams keep you from going crazy . . . Federal Express, which handles 45% of the overnight delivery market, was founded on a plan for which Fred Smith had earned a C-minus in his economics class at Yale. . . . Because of chemical changes, after 45 minutes in the dark humans can see as well as an owl or a lynx, and better than a rabbit or a whippoorwill. . . .

At 4 a.m., on the last night of his life, Elvis Presley played racquet ball and then sat at a piano and played “Blue Eyes Crying in the Rain”. . . . In 1978, the entire crew of a 707 fell asleep and overshot Los Angeles by 100 miles before they woke up . . . . The Muslim definition of dawn is the time when you can tell the difference between a black thread and a white one. . . . The marriage-license bureau stays open round-the-clock on weekends in Las Vegas (“the capital of the American night”), and for $500 the Little White Chapel will marry you in a “Joan Collins Special,” which includes a video of the ceremony, a wedding cake and a French lace hankie.

Although some are dullards, many of the people visited by Coyne, particularly those who deal with the melancholy side of life, are memorable indeed: the Chicago nurse in the trauma ward who often goes home saturated in other people’s blood; the saintly workers at the all-night shelter for the homeless, where Coyne notes a pillowcase on one of the bunks with the stitched philosophy, “Happiness is being one of the gang”; the ever-so-patient night-court judge in New York who warns the thief of eight boxes of chocolates, “You’re going to get pimples”; the Trappist monks in Utah who love to watch “The Sound of Music” (do they dream of renouncing their vows?); the flickering reference to the triple-murderer who, after consuming four double bacon cheeseburgers, two large orders of French fries and a large soda, thanked the state of Nevada “for letting me die with dignity.”

Perhaps the very best of the book--the passages that underscore the exquisite mysteries of the dark hours--is Coyne’s musings over nature’s part in all this. It’s a real pleasure, for instance, to listen to him when he looks up into the night sky over Nebraska: “The history of the universe is up there, too, because each point of light in the night sky is only a memory: the star it comes from might have died long since. Alpha Centauri, the nearest star to Earth besides the Sun, is 4.3 light-years away; the present light started toward us when Ronald Reagan was President. The light from other stars has been traveling since the Civil War, the Italian Renaissance, the Dark Ages. The Andromeda Nebula, the faint patch that looks to the naked eye like just another star, is actually the ancient light of a neighboring galaxy, two million light-years away, filled with 200 billion stars, twice as many as in our own Milky Way galaxy; when the light we now see from it left for Earth, our human ancestors had not yet learned how to make fire. To look up into night here is to be an archeologist of astronomy: you can uncover the skeleton of time.”