From Preface: "A brief description of the method used in compiling these tables and the limitation of coverage are given in the preface to Supplement 1 of the NBS Circular 510. The present volume contains information pertaining to substitution, exchange, and elimination reaction types and extends the material on these types found in NBS Monograph 34, Volume 1. The date on each page gives the year and month to which the literature had been surveyed."

From Abstract: "For about 1500 spectral lines of diatomic molecules observed by coherent radiation techniques, measured frequencies, assigned quantum numbers, and newly computed intensities are given."

Report describing a gravimetric hygrometer that serves as the NBS standard instrument for the measurement of the moisture content of gases on an absolute basis in terms of mixing ratio (mass water vapor/ unit mass of dry gas). The National Bureau of Standards and other laboratory reference and working instruments are compared and calibrated with this instrument. The measuring operation involves the absorption of the water vapor from a water vapor-gas mixture by a solid desiccant and the determination of the mass of this water vapor by precision weighing; it also involves the determination of the volume of the associated gas of known density by counting the fillings of two calibrated stainless steel cylinders. The construction and operation of the instrument is described. Discussions of the tests and calibrations of component parts, and of the sources of errors also are included. There is also an analysis of the random and systematic errors effecting the overall accuracy in the determination of mixing ratio.

Report discussing the VLF, ELF propagation in the earth-ionosphere waveguide emphasizing the total field found by summing all modes which contribute appreciably. Solutions are given and calculations are made for a homogeneous isotropic ionosphere, a homogeneous ionosphere with a constant radial magnetic field imposed, and an ionosphere with a magnetic field of arbitrary dip angle.