THIS BOOK ANSWERS a question that must puzzle any intelligent child: Why are there so many museums of natural history when there is no such subject? Well, long before plate tectonics, long before double helices and charm (I mean the property of sub-atomic particles, not pre-TV charisma), there was a subject called natural history. It was a friendly union of zoologoy, botany, and geology, as well as Victorian England's multi-purpose craze.

For one thing, according to British journalist Lynn Barber, the pursuit of natural history "offered something to do - a hobby -- and there was nothing the middle classes need so badly as something to do. The boredom of the affluent Victorian family is truly frightful to contemplate." Natural history also lent purpose to the inevitable daily walk, which became a hunt for rocks or a raid on tidal pools. Most important for the eminently pious Victorian, doing natural history reinforced belief: Many naturalists were clergymen, and few doubted that familiarity with Nature's ordered plenitude must strength faith in God the Designer.

The Nature craze had phases (the terrarium phase, the aquarium phase), devotees who were famous in other fields (Edward Lear, the nonsense poet, was an excellent ornithological illustrator), and a raft of eccentrics. Of these the most outre may have been Frank Buckland, who as an Oxford student kept a menagerie that included a bear. The bear, "dressed in cap and gown, and accompained by its owner, attended the Oxford meeting of the British Association in 1847 where Lord Houghton 'attempted to mesmerise [the bear] in his corner. This made the bear furious, but he gradually yielded to the influence, and at last fell senseless on the ground.' (Later, Frank's pets were always falling senseless on the ground when he tried out the new miracle of chloroform on them.)" Buckland became renowned as a zoophagist. He once threw a dinner for more than a hundred guests, with courses of Honduras turkey, kangaroo ham, and Japanese sea-slug. "The kangaroo ham was a great success but it emerged afterwards that the waiters had mixed the menu cards, and it was really wild boar."

Though Barber revels in depicting such oddballs in this witty and well-illustrated book, she is also very good at the heavier tasks, such as explaining how Darwin's biology and Lyell's geology remade natural history into a source of religious doubt -- how sermonds in stones became heresies in strata. Keep in mind as the controversies unfold that this was an age when nearly everyone took literally the creation story in the Book of Genesis and supposed God to have handcrafted every species, fully-formed and Hummel-like, at the beginning of time, a scant 6000 years ago.

The first onslaught on received wisdom was the proliferation of known species resulting from voyages and treks. Whereas only a few hundered species had been recorded by the 18th century, by the middle of the 19th there were many thousands. (today the number stands at well over a million, with more coming in every day, although environmentalists warn that extinctions will send it plummeting by the end of the century.) This expansion raised the Noah's Ark problem: How could the patriarch have squeezed two of "every living thing of all flesh" into a vessel measuring 300 by 50 cubits, which the Victorians worked out to "exactly one-seventh of the floor area of the Great Exhibition" of 1851. The favored way out of the dilemma, reinterpreting the Flood as a local disturbance, was "for many laymen . . . the first hint that the Book the Genesis could not always be taken at face value."

Then there was the unmistakable evidence from fossils and formations that the earth was far older than people wanted to admit. The famed naturalist Philip Gosse tried to reconcile fact with credo by positing that God had sown evidence of antiquity "to suggest that the Earth had prior history, when in fact it did not. God created the world in six days in the year 4004 B.C. as the Book of Genesis says, but He implanted it with fossils to make it seem older and to confuse later geologists." This pseudo-solution failed to convince even the most fervent believer.

The most telling attack, of course, came from the pen of Charles Darwin and the voice of his champion, Thomas Henry Huxley. The linchpin of Victorian natural theology was the argument from Design: the manifest order of the world implies its creation by an arranging Mind. Although Hume had exposed this argument as a question-beggar in his Dialogues Concerning Natural Religion, Darwin's work undercut it at the level of fact. The order in the animal world, he showed, is the sum of random adaptations that take hold and "work" in their milieus. On May 20, 1871, the Family Herald declared, "Society must fall to pieces if Darwinism be true," and the heyday of natural history was over.