BOOK REVIEW : Natural Reflections on an Imperfect World : BULLY FOR BRONTOSAURUS: Reflection in Natural History. <i> by Stephen J. Gould</i> . W.W. Norton : $22.95; 524 pages

not a real word at all but the letters on the left side of the top row of English language typewriters--describes, for keyboard aficionados, this particular configuration of letters, numbers and punctuation marks.

Hardly the most efficient arrangement, QWERTY was designed to slow down the strokes to prevent keys in early typewriters from striking each other and getting stuck.

Stephen J. Gould uses the evolution of the keyboard to underline one of the themes--the principle of imperfection--that runs through the 35 essays in this skillful collection.

A professor of geology and curator of invertebrate paleontology at Harvard’s Museum of Comparative Zoology, Gould has probably done more to make natural science accessible to a wide audience than any other living writer. He is a man with a pedagogical mission. After an entertaining description of the peculiar history of the typewriter, Gould concludes that “imperfections are the primary proofs that evolution has occurred, since optimum designs erase all signs of history.”

A second theme--that while humans as pattern-seeking animals look for meaning or purpose in all events, “the probable reality (is) that the universe both doesn’t care much about us and often operates in a random manner”--may not convince every reader. But it is certainly provocative.

Gould is a devout iconoclast and at the same time a true believer that education, especially in history and the laws of nature, can overwhelm ignorance.

In “Of Kiwi Eggs and the Liberty Bell,” Gould debunks the “myth of noble non-Westerners living in ecological harmony with their potential quarrels,” as he describes the way indigenous New Zealanders gobbled into extinction a toothsome species of giant kiwi. And in “The Horn of Triton” he describes the recent liquidation of another species of kiwi by a single wild dog and denounces “as romantic twaddle the litany that man alone kills for sport and other animals only for food.”

Gould’s skill lies in weaving together historical anecdote or the derivation of words with personal experience and in deriving from them lessons in either human or natural history. His bout with cancer demonstrates extraordinary rationality, as well as courage, in the face of terror.

In the shadow of the cold fusion fiasco, it is delightful to learn in “The Chain of Reason Versus the Chain of Thumbs” how, in 1794, Louis XVI set up the first Royal Commission to investigate suspicious scientific claims. The commission, including Benjamin Franklin and Antoine Lavoisier, examined the pretentions of Franz Mesmer that his “mesmerism” cured a host of ills. (They exposed mesmerism as fraud and posited for the first time the efficacy of the power of suggestion as an explanation for some of Mesmer’s reputed successes).

Another historical embarrassment, and a lesson to would-be unified field theorists of biology, is the story of Abbott Handerson Thayer in “Red Wings in the Sunset.” Thayer, a popular 19th-Century American painter, dived into a scientific debate way over his head when he generalized about the adaptive value of animal colors. Thayer considered color useful only for concealment. Putting his painterly experience to work, he correctly identified “countershading” as the device that makes some animals look flat against some backgrounds.

“In countershading, an animal’s colors are precisely graded to counter the effects of sunlight and shadow. Countershaded animals are darkest on top, where most sunlight falls, and lightest on the bottom.”

The reversal in intensity of coloration cancels out shadows, leaving a uniform color so that an animal is invisible to predators. Thayer crowed, in an ornithological journal, that his “newly discovered law” explains, once and for all, the advantage of animal coloration.

A good explanation for one phenomenon, sometimes, but absurd as a universal principle. Thayer stretched his explanation to the breaking point when he rationalized that a flamingo’s brilliant red wings make it invisible at a certain time of day, in certain places, if it happens to be silhouetted against the sunset. The lesson: “Such monistic systems never work. . . . Diversity reigns at the superficial level--the unifying principles are deeper and more abstract.”

Some of these essays appeared previously in Natural History magazine. The great advantage to reading them here is that Gould corrects what in one instance proved to be an error (illustrating the self-correcting nature of science) and on occasion adds some of the correspondence the columns provoked when first published, a reflection of the thriving community of amateur and professional natural historians in the United States.

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