IN MAY of 1883 a pretty American girl named Maud Du Puy arrived in Cambridge, England, to visit relatives. They were very well-placed relatives indeed. Her Uncle Dick and Aunt Cara, later Sir Richard and Lady Jebb, knew everyone in the city worth knowing.

It was a marvelous time for pretty girls to be visiting Cambridge. The faculty at 18 of the 20 colleges then making up Cambridge University was 100 percent male -- and, better yet, about 90 percent unmarried. This was not because all those clever men loved celibacy. It was because of the university rules. For 600 years after the founding of Cambridge, the rules said that the fellows of the colleges must be bachelors, living in college and devoting their time to study. The only ones allowed to get married were the 18 masters of the 18 men's colleges, the two mistresses of the two women's colleges, and a few holders of professorships. It wasn't until 1878 that the Revised Statutes came into effect, and the colleges gradually began to permit ordinary faculty members to have wives. In 1883, when Maud arrived, mating fever was at a peak.

Uncle Dick had been a fellow of Trinity College, the largest and most famous at Cambridge. Naturally his niece met a lot of the dons at Trinity. By midsummer, no less than three of them were in hot pursuit.

Maud took this calmly. "The English girls are so awfully susceptible," she wrote home; "if a man speaks to them almost, they instantly think he is desperately in love with them." And then she adds, "I am not at all susceptible, and that is one difference between them and me."

Still, one of the three did finally catch her. In 1884 Maud Du Puy was married to George Darwin, second son of the great Charles Darwin, fellow of Trinity, and the newly elected Plumian Professor of Astronomy. (She made him come to Erie, Pennsylvania, for the ceremony.) He was 38, she 22.

The happy couple -- they really were -- bought a big house in Cambridge called Newnham Grange, and settled down to a high-Victorian life. It was tempered on one side by American independence and on the other by Darwinian eccentricity. In due course they had four children. One grew up to marry Lord Geoffrey Keynes, another, named for his grandfather, to be a physicist Sir Charles Darwin (1887-1962), a third to be a distinguished artist.

All this is prologue to Period Piece , a recollection of that era by one of the participants. Gwen Raverat was the daughter who grew up to be an artist. In this book she tells what it was like to be in that first generation of faculty children, and also What it was like to be a Darwin surrounded by other Darwins. There are few memoirs more charming.

To be a faculty child at Cambridge in the 1880s was to be extraordinarily privileged, and also to be extraordinarily repressed. There was nothing of genteel poverty at Newnham Grange; there was opulence. The house was full of cooks, governesses, and ladies' maids. Its grounds ran along both sides of the river Cam for quite a stretch, and even included two islands in the river, on one of which Maud kept a flock of hens, who had their own private bridge to the shore.

Yet, nearly everything a child might want to do was forbidden on principle. It was too dangerous, or it was unrefined, or it was bad for the character. Even bacon for breakfast was bad for the character, and little Gwen Darwin never tasted that delicacy until she was almost 10. "It is true," she adds, "that twice a week we had, at the end of breakfast, one piece ot toast, spread with a thin layer of that dangerous luxury, Jam. But, of course, not butter, too. Butter and Jam on the same bit of bread would have been an unheard-of-indulgence -- a disgraceful orgy."

As for that birthright of even the porrest child in 1981, the candy bar, it was forbidden on two separate grounds. Not only was it held to give the child too much pleasure, it was thought to be unwholesome -- loaded by the manufacturer with cheap adulterants. Hence an added thrill of going on trips. The one exception was the butterscotch you could get from penny-in-the-slot machines on railway platforms. "There was a blessed theory that slot machines were pure, that the Railways guaranteed their Virtue."

With local variations from family to family, this sort of thing was common to the whole educated upper middle class in England then, as was the expectation that a girl of 6 couldn't go outdoors without a hat on, or that one of natural duties was to be a chaperon to her unmarried aunts and cousins when a gentleman called.

But there was also a special way of life that applied just to Darwins, and it is in describing this that the book reaches it very best. The family that Maud Du Puy married into was large. George Darwin had six brothers and sisters, half of them living in Cambridge. It was also distinguished. Three of the five boys were eventually knighted; nearly everyone was an intellectual. But most of all, it was a family of totally unself-conscious eccentrics. They didn't worry about their images -- they almost didn't know they had images.

Aunt Etty, Charles Darwin's eldest daughter, was perhaps the supreme eccentric, wearing her extraordinary homemade germ-mask ("it tied on like a snout") while receiving visitors. But Uncle William comes close. One of my favorite moments in the book describes his behavior at his father's funeral, which was a state occasion in Westminster Abbey. The question of dignity simply didn't occur to him. "He was sitting in the front seat as eldest son and chief mourner, and he felt a draft on his already bald head; so he put his black gloves to balance on the top of his skull, and sat like that all through the service, with the eyes of the nation upon him."

It is the calm delight that Mrs. Raverat takes in incidents like this that makes her such a joy to read. Her style is remarkable. On the one hand, she had something close to total recall of her childhood: the emotions as well as the events. Many children, myself among them, have thought that no adult understands what it feels like to be a child, and have vowed that when they grow up, they'll never, ever forget. Few of us manage to keep that vow. She did.

On the other hand, she wrote Period Piece when she was in her late sixties, a wise old lady. By then she had come to have that amused but loving tolerance for human failings that I associate with the best kind of grandmothers. The combination of childish immediacy and adult understanding is wonderful. Seldom have so much humor and so little malice coexisted.

The book has one final pleasure. Besides writing the text, Mrs. Raverat drew and captioned about 75 illustrations, which come to have a life of their own. They exhibit the same positive delight in the absurdities of human life that the writing does, and the same child's-eye freshness.

If you were going to read only one book in your life about a group of Victorians, I'd say forget Lytton Strachery, even forget Steven Marcus, and read Period Piece .