This journal provides immediate access to some articles. Volume 2(9); September 1916 Astronomy The Rotation and Radial Velocity of the Spiral Nebula N. G. C. 4594 PMCID: PMC1091084 A Simple Method for Determining the Colors of the Stars PMCID: PMC1091085 Studies of Magnitudes in Star Clusters: III. The Colors of the Brighter Stars in Four Globular Systems PMCID: PMC1091086 Mathematics A Proof of White's Porism PMCID: PMC1091088 On Certain Asymptotic Expressions in the Theory of Linear Differential Equations PMCID: PMC1091092 On Newton's Method of Approximation PMCID: PMC1091093 Petrology A Contribution to the Petrography of the Philippine Islands PMCID: PMC1091089 Physics The Effect of an Electric Field on the Lines of Lithium and Calcium PMCID: PMC1091087 Physiology The Mechanism of Diffusion of Electrolytes Through Animal Membranes PMCID: PMC1091083 Salt Antagonism in Gelatine PMCID: PMC1091090 Similarity in the Behavior of Protoplasm and Gelatin PMCID: PMC1091091 Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||