BOOK REVIEW : Travelogue Takes Dutiful Trip to Sydney : SYDNEY, <i> by Jan Morris,</i> Random House, $22.50; 242 pages.

The whole idea of being a “travel writer” is strange, really. You travel somewhere, you take notes, you write your book, and then you travel somewhere else. Your observations are authentic--they must be because you have seen them--but they are limited by time and space and your own literary agenda. Who is the audience for these “travel” books? People who have not been, nor will ever go, to the place in question. Because people who have been to Paris, Singapore, Cairo, Rio, San Blas, will begin to rise up; to make disrespectful notes in their margins and shout: “It’s not that way at all!” People who actually live in that place being “traveled” might either grunt, go to sleep or go ballistic.

Jan Morris has written a competent, chronological, amusing, mannerly, dutiful account of one of the most beautiful and enchanting cities in the world: Sydney, Australia. My gut feeling is: She found a nice apartment with a great view of the harbor, checked a dozen books out of the local library (including a collection of colorful epitaphs from a historical Sydney cemetery and the Oxford Companion to Australian Literature) and then sat demurely down to write.

Jan Morris’ “Sydney” is very useful. Its tone is very pleasant, but pretty soon you want to grab her by the lapels of her blazer and shriek: “Open your eyes! You’re talking about what possibly may be the most beautiful city in the entire world! A city with what just may be the most heroic municipal history in the entire history of man! A city where the arts right now--novels, film, pictorial art, theater--are going ape-crazy with creativity!” It’s as if Morris had visited Mexico City and described it as “crowded,” or announced Paris traffic to be interesting but clogged.

If I read correctly, Morris’ agenda here, based on many of her other travel books, is the decline and ebb of the British Empire. Seen in that context, Sydney must be seen in shadow. But what if you took it out of that context? What if you first read Robert Hughes’ “The Fatal Shore,” the passionate, hair-raising, blood-drenched history of Eastern Australia as the most cruel and horrible prison camp for English people in all of recorded history?

What if you read about criminals who were flogged so mercilessly that their backbones, over time, became polished and exposed, so that their bones came through their skin and stayed there? A place where little children took hands and voluntarily jumped off cliffs to their deaths, because life itself was purely unbearable?

And what if these people, 83,000 of them, by 1840, accompanied by their brutish jailers--surely the most extended dysfunctional “family” in all of human history--over the period of only 200 years got a grip, and created an earthly paradise, where businessmen take long lunches and sing into the afternoon, and each house has its garden, and the mornings are placid, and the harbor-- by far the most gorgeous harbor in the world--swirls and ebbs, and more businessmen step into little boats in twilight fog and chug from work to home and back again: Well, what an astonishing accomplishment--to change the unspeakable to the sunnily domestic, over a period of only two centuries.

Morris takes another tack, and, after all, it is her book. Remember “The First Family”--the screamingly funny parody of the Kennedy family by Vaughn Meader, hastily pulled from the market after the President was assassinated?

In that album, the First Lady, high-pitched and breathy, gave a tour to show the new art in the White House: “Well,” she said, “there’s this one and this one and then there’s this one . . . .” Jan Morris does this for Sydney.

We hear about the First Fleet and the First Governor. We hear about the Father of Agriculture and the Father of Flight. We are given extensive lists of Flora and Fauna and 10 Representative Men who got rich.

We are given lists of immigrants: Greeks, blacks, Chinese, Jews, Vietnamese. We are told that hard liquor is more popular in Sydney than sex and that the Beach Culture probably more popular than either. (But a 1900 bubonic plague epidemic is blown off in half a sentence.)

She likes those epitaphs, though. And if you’re into whimsical footnotes, this book’s for you. More than anything, if you’re glued to your couch and can’t go anywhere this summer, you will be consoled by this book; and you won’t feel so bad about not going.