Fig. 1. Velocitydistance relation among extra-galactic nebulae. Radial
velocities, corrected for solar motion (but labeled in the wrong units),
are plotted against distances estimated from involved stars and mean
luminosities of nebulae in a cluster. The black discs and full line
represent the solution for solar motion by using the nebulae individually;
the circles and broken line represent the solution combining the nebulae
into groups; the cross represents the mean velocity corresponding to
the mean distance of 22 nebulae whose distances could not be estimated
individually. [Reproduced with permission from ref. 1 (Copyright 1929,
The Huntington Library, Art Collections and Botanical Gardens).]