. The semi-centennial anniversary of the National Academy of Sciences, 1863-1913 . Fig. 3. The Non-magnetic Yacht Fig. 4. Direct Photograph of Part of the Sun,April 30, 1908. THE SEMI-CENTENNIAL ANNIVERSARY 41 Here is a photograph of the sun, as it appears in the telescope(Fig. 4*). Scattered over its surface are sun-spots, which in-crease and decrease in number in a period of about years. Itis well known that a curve, showing the number of spots on thesun, is closely similar to a curve representing the variations ofintensity of the earths magnetism. The time of maximum sun-spo
. The semi-centennial anniversary of the National Academy of Sciences, 1863-1913 . Fig. 3. The Non-magnetic Yacht Fig. 4. Direct Photograph of Part of the Sun,April 30, 1908. THE SEMI-CENTENNIAL ANNIVERSARY 41 Here is a photograph of the sun, as it appears in the telescope(Fig. 4*). Scattered over its surface are sun-spots, which in-crease and decrease in number in a period of about years. Itis well known that a curve, showing the number of spots on thesun, is closely similar to a curve representing the variations ofintensity of the earths magnetism. The time of maximum sun-spots corresponds, as Dr. Bauer found, with that of reducedintensity of magnetization of the earth, and the parallelism of thetwo curves is too close to be the result of accident. We maytherefore conclude that there is some connection between thespotted area of the sun and the magnetic field of the earth. We shall consider a little later the nature of sun-spots, but forthe present we may regard them simply as solar storms. Whenspots are numerous the entire sun is disturbed, and eruptivephenomena, far transcending our most
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscience, bookyear1913
