(1912). XXXII. On the diffusion of actinium emanation and the active deposit produced by it. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 24, No. 141, pp. 370-379.
RECENT investigators have studied the thermal expansion, the electrical resistance, the elastic constant, the thermoelectric and the photoelectric effects of single crystals of metals, but up to the present few accurate results have been obtained for the fundamental para- or diamagnetic properties of such metals.
The interest in the Aurora Borealis and the problems associated with it, is evidenced by the extensive list of careful investigations that have been published upon this subject. Since the early work of Angstrom, we have the published records of over a hundred investigations on the spectrum, and many others on the origin or other phenomena characteristic of the aurora. Paulsen, Westman. Sykora, Vegard, and others have determined the wave-lengths of many of the lines of the general auroral spectrum, while, recently, Slipher, Rayleigh, and Babcock, have studied the light of the night sky. Babcock, using a Fabry and Perot interferometer, determined very accurately the wave-length of the auroral green line 5577. The precision of his measurements is in marked contrast to those obtained with low dispersion spectrographs. The laboratory experiments on the excitation of the auroral spectrum have not been less numerous than the spectroscopic investigations. The more recent work has been carried out by Stark. Rayleigh, and Vegard. After a careful examination of all the results obtained in these reports, we may only say that the exact nature of the cosmical rays, responsible for the aurora, remains a mystery.
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