Smithsonian Scientific Series

SMITHSONIAN SCIENTIFIC SERIES Editor-in-chief CHARLES GREELEY ABBOT, D. Sc. Secretary of the Smithsonian Institution Published by SMITHSONIAN INSTITUTION SERIES, INC. NEW YORK. The solar spectrum. Sir Isaac Newton suggested seven colors violet, indigo, blue, green, yellow, orange, red but its hues are really innumerable and merge insensibly into one another This unique reproduction of the spectrum was obtained by a new method originated by Mr. Charles A. Grotz, President of the Trichromatic Engraving Company, Inc., New York THE SUN AND THE WELFARE OF MAN By CHARLES GREELEY ABBOT, D. Sc. Secretary of the Smithsonian Institution VOLUME TWO OF THE SMITHSONIAN SCIENTIFIC SERIES 1929 COPYRIGHT 1919, BY SMITHSONIAN INSTITUTION SERIES, IKC. Printed in the United States of America AH rights reserved Koforanc Copyright Under the Articles of the Copyright Convention of the Pan-American Republics and the United States, August n 1910 CONTENTS I. WHY STUDY THE SUN i II. FROM SHORE TO DESERT MOUNTAINS, MEAS URING SUN RAYS 10 III. THE ENDS OF THE EARTH, THE SUN, AND THE WEATHER. i 41 IV. MEASURING INSTRUMENTS FOR SOLAR RAYS 74 V. THE ATMOSPHERE. WHAT HAS IT TO DO WITH SOLAR RADIATION 98 VI. A DAY IN THE FIELD 121 VII. SOLAR VARIATION AND WEATHER . . . 138 VIII. A SOLAR OBSERVATORY AMONG THE HOT TENTOTS 172 IX. HARNESSING THE SUN 194 X, SUN RAYS, PLANTS, AND ANIMALS . . . 223 XI. DOES THE SUN MAKE OTHER WORLDS HAB ITABLE 242 XII. THE LANDSCAPE OF THE SUN .... 254 XIII. ECLIPSES 265 XIV. OUR SUN A VARIABLE STAR 287 APPENDIX. THE A B C OF LIGHT AND RADIATION 302 INDEX 319 ILLUSTRATIONS LIST OF PLATES Solar Spectrum in color Frontispiece 1. Smithsonian solar station at Montezuma, Chile .... 4 2. Livingquarters at Smithsonian Observatory in Chile . . 5 3. Fossil footprints 8 4. The bright and dark spectrum of iron 9 5. A. Prof. C. A. Young 12 B. William Thaw 12 6. Dr. John A. Brashear 14 7. Secretary Langleys page proof 16 8. A. Dr. Anders Jonas Angstrom 20 B. Dr. Knut Johan Angstrom 20 C. Dr. Anders Knut Angstrom 20 9. Telescopes of Mount Wilson Observatory 21 10. Edward Everett Hale 24 n. Smithsonian solar station on Mount Wilson 28 12. Smithsonian solar station on Mount Whitney .... 29 13. Smithsonian solar-radiation expedition to Bassour, Algeria 32 14. The Cadi, at Bassour, Algeria 33 15. Up from the Sahara desert . 36 16. Thou shalt not muzzle the ox 37 17. Music at Bassour, Algeria 40 18. Balloon pyrheliometer 44 19. Sir Frank Dyson 56 20. Smithsonian solar-radiation observatory, Table Mountain . 64 21. Group of apparatus for measuring energy of solar rays . 80 22. Electrically driven rotating sectors 84 23. Assistant Baughman, with silver-disk pyrheliometer . . 85 24. Abbots pyranometer 92 25. Lord Rayleigh 96 26. Three eminent American scientists 100 27. Snow crystals 101 08. Cloud-banner on Mount Assiniboine 104 29. A sea of fog below Mount Wilson 108 30. Alto-cumulus and cumulus clouds near Mount Wilson . . 109 31. Scarf cloud over cumulus, Mount Shasta 112 32. Tornado near Elmwood, Neb 113 33. Field outfit for measuring sun and sky rays 128 34. Director Moore reducing observations 129 35. The Earl of Rosse 136 36. Mr. F. E. Fowle 152 37. Spiral nebula 160 38. Street scene in Bombay 172 39. Posing great snake at Agra 173 40. Observatory of emperor-mathematician, Jai Singh II. . . 176 41. In the streets of Agra 177 42. On the plains of Baluchistan 180 43. Performers innative African dance, Johannesburg . . . 18 1 44. In Durban, South Africa. Mrs. Abbot and her rickshaw man 188 45. A Hottentot village, South West Africa 189 46. Cottage of solar observers on Mount Brukkaros . . . 192 47 Water-carriers at radiation station, Mount Brukkaros . . 193 48. A. Mouchots multiple-tube sun-heat absorber .... 196 B. Ericssons sun-power plant 196 49. A. Adams solar cooker 197 B. Pifres sun-power plant 197 50. Eneass sun-power plant at Pasadena ...... 204 51. The Shuman-Boys solar engine at Meadi, Egypt . . . 205 52. Abbots solar cooker 216 53...