One of the charms of New Yorker writer and physicist Jeremy Bernstein is that he is not afraid to put himself into his narratives. He told Lives-of-a-Cell biologist Lewis Thomas, for example, that he thought new diseases so likely that it was logical to quarantine astronauts returning from the moon--this, after Thomas had declared such possibilities nil. Then there was the time Bernstein asked John von Neumann if the computer might some day replace the human mathematician, to which the Great Man replied: ""Sonny, don't worry about it."" This collection of mostly New Yorker pieces includes two on hard science, studies of Kepler and Nobel physicist I. I. Rabi; three on biologists--Lysenko, the late X-ray diffractionist Rosamond Franklin, and Thomas; and a third section on Fact and Fantasy, where the von Neumann anecdote appears in an article on serf-replicating machines and there's also a charming profile of Arthur Clarke. Best, possibly because of Bernstein's intrinsic talents and experience, are the hard science pieces, especially the Rabi profile. Even when not wholly successful, however, Bernstein is to be complimented for entering domains few would assay. If he fails to explain everything satisfactorily, he goes about the attempt with an incisive intelligence and a fluent style, assuring that the reader will come away with a few choice nuggets if not pure gold.