The authors have obtained high signal-to-noise spectra of Seyfert 1 galaxies in order to study the broad emission line profiles. Three contamination effects that tend to weaken the core or strengthen the wings of the H-beta profile relative to the H-alpha profile are considered. Despite corrections applied to the profiles for these effects, the H-beta/H-alpha ratio increases dramatically with the absolute value of the radial velocity in eight of the nine galaxies studied. From a comparison of these profile ratios among individual Seyfert 1 galaxies, it is found that the broad-line region clouds are in a roughly spherical distribution around the photoionizing continuum source. If H-beta/H-alpha and He I 5816 A/H-beta increase primarily with the ionizing flux, as recent photoionization models suggest, then clouds closer to the continuum source must have higher velocities on average. Finally, the large increase in H-beta/H-alpha and He I/H-beta from the core to the wings indicates that the broad-line region is not a thin spherical shell.
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D. M. Crenshaw (1986) studied this question.