This journal provides immediate access to some articles. Volume 16(7); July 15, 1930 Astronomy ON THE SYSTEMATIC AND ACCIDENTAL ERRORS OF MODERN TRIGONOMETRIC PARALLAXES PMCID: PMC526672 ON THE DISTANCES AND RADIAL VELOCITIES OF EXTRA-GALACTIC NEBULAE, AND THE EXPLANATION OF THE LATTER BY THE RELATIVITY THEORY OF INERTIA PMCID: PMC526673 Chemistry THE STRUCTURE OF SOME SODIUM AND CALCIUM ALUMINOSILICATES PMCID: PMC526670 Mathematics THE CELLULAR DIVISION AND APPROXIMATION OF REGULAR SPREADS PMCID: PMC526674 NORMAL COÖRDINATES IN THE GEOMETRY OF PATHS PMCID: PMC526675 Physics THE CRYSTAL CLOCK PMCID: PMC526676 THE BAND SPECTRUM OF OZONE IN THE VISIBLE AND PHOTOGRAPHIC INFRA-RED PMCID: PMC526677 ON THE ESTIMATION OF DISTANCES IN A CURVED UNIVERSE WITH A NON-STATIC LINE ELEMENT PMCID: PMC526678 Physiology and Pathology THE DEMONSTRATION THAT ALLERGIC INFLAMMATION IS NOT NECESSARY FOR THE OPERATION OF ACQUIRED IMMUNITY PMCID: PMC526671 Zoölogy EXPERIMENTS IN BIRD MIGRATION. II. REVERSED MIGRATION PMCID: PMC526679 Journal Matter Administrative content — journal masthead, notices, indexes, etc. | ||