<i> Manhattan ’45 by Jan Morris (Oxford University: $17.95; 273 pp., illustrated) </i>

Jan Morris’ “Manhattan ‘45” is a delightful crawl through the Wonder City at the end of World War II. The year 1945 wasn’t a random choice. The book is about a particular time and place in a very particular world. Morris contrasts the “shimmering, bright, rich and wonderfully entertaining metropolis, and the gray shadowed capitals of Europe.”

New York was one of the few great world cities that prospered during the war. “This crowded island was the head, the brain, the essence of America, and the idea of America was omnipotent then.”

Manhattan “was the Present tantalizingly sublimated. It was the Future about to occur,” and thus an island at the very edge of its own magnificence. “New York was never to lose its excitement, its power to move, its limitless energy; but never again, perhaps, would it possess the particular mixture of innocence and sophistication, romance and formality, generosity and self-amazement.”

Morris chose the title “Manhattan ‘45” because it “sounded partly like a kind of gun, and partly like champagne.” She means to celebrate Manhattan’s thunder and power. She is not interested in sociology or dark portraits. Here is “an outsider’s book, about the public rather than the private city.” She sees “Manhattan ‘45” as “an exercise in affectionate and light-hearted imagination.” And Morris is successful in most of her desires. She creates a wondrous tapestry, a texture of detail, that few other writers might have been able to find. The past is evoked for us, the moment is lived, without nostalgia or sentiment. Morris reminds us of a city that was dominated by the presence, the feel, and the smell of ships. In 1945, “there was almost as much traffic in the harbor as there was on the streets, and billowing black clouds of steamship smoke habitually drifted over the waters. Wherever you looked out there, sea-shapes were moving.”

Movement is what Manhattan was about. “Half this city’s skills and aspirations seemed to go into the propagation of motion.” The landscape itself had its very own rhythm, a kind of dynamic pull. Manhattan had an architecture of “frozen movement. It did not look built to stand still.” The island itself had a crazy swagger, a confidence, as if it were poised to explode. It seemed both murderous in its energy . . . and romantic. “Towering island on the edge of a continent, facing the wild ocean, Manhattan was as truly romantic a city as Venice itself.”

And it is romance and movement that Morris captures in “Manhattan ‘45”: the myth of Fiorello LaGuardia, the mayor who could never stand still; the city’s one game warden, who went around in a ranger hat, making sure that wild animals weren’t cooked in restaurants; the private railroad sidings below the Waldorf-Astoria, where the very rich could arrive in their own railroad cars; messengers on roller skates delivering packages for Macy’s; the Rockettes living like “odalisques” in backstage dormitories at Radio City Music Hall; the constant movement of river traffic; drinking coffee at the Automat from spouts designed with a dolphin’s head; the doomed life of the Manhattan trolley and the double-decker bus.

Morris takes us back to Manhattan ’45 to witness all sorts of beginnings and endings, to collect the myth of Manhattan. But there is one flaw in the book. Morris’ first trip to Manhattan wasn’t until 1953, and the Manhattan she reveals to us isn’t wed to her own psyche with any sense of magical loss. Thus, she conjures up a dream city out of other people’s facts and notes. There is nothing particularly wrong with this, except that the book suffers from some unfortunate cliches. Manhattan’s slums, she tells us, “burst with vivacity.” But she never articulates the despair behind this colorful life. The Italians, she says, had their Little Italy, but they were “dispersed all over the city too, and their reputation ran the whole Italianate gamut, from the folksy familial, all mamas and homemade pasta, to the Sicilian conspiratorial, all vendettas and submachine guns.” But she cannot tell us very much about that lean, everyday life outside pasta or submachine guns.

And what of the blacks, who were mostly invisible in 1945, stuck in that wondrous ghetto of Harlem? “The one thing that black people were universally recognized as being good at was enjoyment.” And so we have the standard myth of blacks being like little children who loved to play. And the myth of Central Park? It was the safest of places, because “almost nobody would have the heart to pick a pocket or grab a passing purse.”

“Manhattan ‘45” is a valuable book in spite of a certain naivete. Morris has imagination and wit, and an exuberant sense of what Manhattan must have been like: At its best, “Manhattan ‘45” is a lyric rediscovery of an island that was about to become the capital of the world.