. The semi-centennial anniversary of the National Academy of Sciences, 1863-1913 . Fig. 9. Zeeman Doublet Photographed in Laboratory Spectrum. Themiddle section shows the doublet. The adjacent sections indicate the appear-ance of the spectrum line in the absence of a magnetic Fig. 10. a, b, spectra of two sun-spots. Thetriple line indicates a magnetic field of 4500gausses in a, and one of 2900 gausses in b. THE SEMI-CENTENNIAL ANNIVERSARY 47 mind. It is not unlikely that the bipolar group is due to a singlevortex, of the horse-shoe type, such as we may see in water afterevery sweep of
. The semi-centennial anniversary of the National Academy of Sciences, 1863-1913 . Fig. 9. Zeeman Doublet Photographed in Laboratory Spectrum. Themiddle section shows the doublet. The adjacent sections indicate the appear-ance of the spectrum line in the absence of a magnetic Fig. 10. a, b, spectra of two sun-spots. Thetriple line indicates a magnetic field of 4500gausses in a, and one of 2900 gausses in b. THE SEMI-CENTENNIAL ANNIVERSARY 47 mind. It is not unlikely that the bipolar group is due to a singlevortex, of the horse-shoe type, such as we may see in water afterevery sweep of an oar. We thus have abundant evidence of the existence on the sunof local magnetic fields of great intensity—fields so extensive thatthe earth is small in comparison with many of them. But howmay we account for the copious supply of electrons needed togenerate the powerful currents required in such enormouselectro-magnets? Neutral molecules, postulated in theories ofthe earths field, probably will not suffice. A marked preponder-ance of electrons of one sign seems to be indicated. An interesting experiment, due to Harker, will help us a pair of carbon rods, insulated within a furnace heatedto a temperature of two or three thousand degrees. The outerends of the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscience, bookyear1913
