THE DISCOVERY OF PULSARS, or rapidly pulsating radio sources, was, like certain other historic events in astronomy, an accident. It is reminiscent of the unexpected detection of radio bursts from Jupiter by Bernard F. Burke and Kenneth L. Franklin, who were studying the Crab Nebula, and of the discovery of the cosmic fireball radiation by Arno A. Penzias and R. W. Wilson, who had intended to survey the galactic continuum at high latitudes.