Apparent Velocity-Shifts in the Spectra of Faint Nebulae

Apparent velocity-shifts of the spectral lines of 46 extra-galactic nebulae have been observed at Mount Wilson, 9 of them by F. G. Pease. Most of these objects are fainter and more distant than any heretofore observed; approximately haff of them are cluster nebulae. With one exception these observations confirm Hubble's velocity-distance correlation and provide numerical data which may be used in discussions of the signifi- cance of the red-shift of spectral lines. For all faint nebulae the displacements are large and toward the red, the maximum of the continuous spectrum shifting also. The largest apparent velocity-shift observed, +19,700km/sec., is that of the bright- est nebula in W. H. Christie's cluster in Leo. Its photographic magnitude is i6.8. With the exception of N.G.C. 205, classified as F5, the spectral types of all the nebulae having absorption lines fall within the narrow limits GI-G5