PHOTO CREDITS
| [Cover] | The Metropolitan Museum of Art |
| [Page facing inside cover] | The “Horsehead” Nebula in Orion. Hale Observatories. |
| [Author’s Photo] | Jay K. Klein |
| [Contents page] & [page 4] | Lick Observatory |
| Page | |
| [7] | New York Public Library |
| [9] | From Discovery of the Elements, Mary E. Weeks, Chemical Education Publishing Company, 1968. |
| [12] | Library of Congress |
| [15] | Sir George Thomson |
| [18] | Burndy Library |
| [19] | New York Public Library |
| [21] | Copyright © 1965 by Barbara Lovett Cline, reprinted from her volume The Questioners: Physicists and the Quantum Theory by permission of Thomas Y. Crowell Company, Inc., New York. |
| [22] & [23] | Curie Foundation, Institute of Radium |
| [26] | Academic Press, Inc. |
| [29] | Van Nostrand Reinhold Company |
| [31] | Top, Nobel Institute; bottom, from Discovery of the Elements, Mary E. Weeks, Chemical Education Publishing Company, 1968. |
| [32] | From Discovery of the Elements, Mary E. Weeks, Chemical Education Publishing Company, 1968. |
| [34] | Top, Nobel Institute; bottom, Niels Bohr Institute. |
| [36], [42], [44], & [45] | Nobel Institute |
| [48] | Academic Press, Inc. |
| [49] | From Discovery of the Elements, Mary E. Weeks, Chemical Education Publishing Company, 1968. |
| [60] | Curie Foundation, Institute of Radium |
★ U.S. GOVERNMENT PRINTING OFFICE: 1975—640—285/13