NONFICTION - Jan. 30, 1994

THE COMMON BUT LESS FREQUENT LOON AND OTHER ESSAYS by Keith Stewart Thomson (Yale University Press: $22.50; 192 pp.). Many of the essays in this volume first appeared in the journal American Scientist, meaning they are directed toward the professional rather than the lay reader. Others, though, are readily accessible even to the non-specialist--especially if you like fish, for Keith Thomson, president of the Academy of Natural Sciences in Philadelphia and the former arts and sciences dean at Yale, is a paleoichthyologist (no doubt he hates the term). In “The Shape of a Shark’s Tail,” Thomson shows how preconceptions can lead researchers astray, to the point that they forget to drop their models and observe nature directly; in “The Puzzle of Palaeospondylus ,” he describes a youthful trip to northern Scotland to collect fossil fish, and how the unresolved scientific battle over the identification of one particular species has haunted him to this day. The best essay here, though, is the autobiographical “Becoming a Scientist”--probably because it shows how an academic ne’er-do-well, given inspiration and direction, can succeed beyond his wildest imaginings.