XXV111 CONTENTS 



yyy. Distribution in normal spectrum of sunlight and skylight, Mt. 



Wilson 6il 



778. Air masses 611 



779- 5^ elements known in the sun's atmosphere 612 



780. Quantitative estimates of composition of solar atmosphere . .613 



781. Abundance of elements in sun, earth and meteorites .... 614 



782. Abbot-Priest solar-energy curve, sea-level 614 



783. Constellation abbreviations (Astron. Union, 1922) 615 



784. Occurrence and abundance of elements in the stars 615 



785. Stellar systems 616 



786. Stellar spectra and related characteristics 617 



787. The Harvard spectrum classification 617 



788. Log (no. stars) /(sq. degree) brighter than photographic magni- 



tude, m, at stated galactic latitudes 618 



789. Numbers and equivalent light of the stars 618 



790. The first-magnitude stars 619 



791. Stars known to be within five parsecs of the sun 619 



792. Percentage of stars of various spectrum classes 620 



793. Galactic concentration of various spectrum classes 620 



794. Distribution of binaries as to spectrum class 620 



795. Masses of spectroscopic binaries, Sun=i 620 



796. Russell diagram [Adams] 621 



797. Spectrum types and absolute magnitudes [Stromberg] 622 



798. Brightness of the stars 623 



799. Giant and dwarf stars 623 



800. Masses and densities 623 



801. Parallax and mean apparent magnitude 624 



802. Spectrum type and mean absolute magnitude 624 



803. Reduction of visual to bolometric magnitude 624 



Stellar Motions 



804. Summary, elements of solar motion (Campbell, 1928) 625 



805. Elements of solar motion (Charlier, 1926) 625 



806. Stars of large proper motion 625 



807. Spectrum class and proper motions 626 



808. Equipartition of energy in stellar motions 626 



809. Stars of large space velocity, greater than 300 km/sec 627 



810. Stars of small space velocity, 5 km/sec. or less 627 



811. Motions of the stars 628 



812. Known stars of radial velocity greater than 100 km/sec 628 



Binary Stars 



813. Visual binary stars . . . . 629 



814. Spectroscopic binary stars 629 



