The CREATION of SCIENTIFIC EFFECTS Jed Z. Buchwald is the Bern Dibner Professor of the History of Science at MIT and direc­ tor of the Dibner Institute for the History of Science and Technology, which is based at MIT. He is the author of two books, both published by the University of Chicago Press: From Maxwell to Microphysics: Aspects ofElectromagnetic Theory in the Lost Quarter ofthe Nine­ teenth Century (1985) and The Rise of the Wove Theory of Light: Aspects of Optical Theory and Ex­ periment in the First Third of the Nineteenth Century (1989). The University of Chicago Press, Chicago 60637 The University of Chicago Press, Ltd., London © 1994 by The University of Chicago All rights reserved. Published 1994 Printed in the United States of America 03 02 01 00 99 98 97 96 95 94 1 2 3 4 5 ISBN: 0-226-07887-6 (cloth) 0-226-07888-4 (paper) Library of Congress Cataloging-in-Publication Data Buchwald, Jed Z. The creation of scientific effects: Heinrich Hertz and electric waves I Jed Z. Buchwald. p. cm. Includes bibliographical references and index. 1. Electric waves. 2. Hertz, Heinrich, 1857-1894. 3. Physicists-Germany. I. Title. QC661.B85 1994 537-dc20 93-41783 CIP @ The paper used in this publication meets the minimum requirements of the American Na­ tional Standard for Information Sciences-Permanence of Paper for Printed Library Materials, ANSI Z39.48-1984. • • • CONTENTS List of Figures vii List of Tables xi Preface xiii ONE Introduction: Heinrich Hertz, Maker of Effects 1 PART ONE: In Helmholtz's Laboratory Two Forms of Electrodynamics 7 THREE Realizing Potentials in the Laboratory 25 PART Tho: Information Direct from Nature FOUR A Budding Career 45 FIVE Devices for Induction 59 SIX Hertz's Early Exploration of Helmholtz's Concepts 75 PART THREE: Berlin's Golden Boy SEVEN Rotating Spheres 95 EIGHT Elastic Interactions 104 NINE Specific Powers in the Laboratory 113 TEN The Cathode Ray as a Vehicle for Success 131 PART FOUR: Studying Books ELEVEN Frustration 177 TWELVE Hertz's Argument 189 ThIRTEEN Assumption X 203 PART FIVE: Electric Waves FOURTEEN A Novel Device 217 FIFTEEN How the Resonator Became an Electric Probe 240 SIXTEEN Electric Propagation Produced 262 SEVENTEEN Electric Waves Manipulated 299 EIGHTEEN Conclusion: Restraint and Reconstruction 325 vi CONTENTS ApPENDIXES 1. Waveguides and Radiators in Maxwellian Electrodynamics 333 2. Helmholtz's Derivation of the Forces from a Potential 340 3. Helmholtz's Energy Argument 348 4. Polarization Currents and Experiment 351 5. Convection in Helmholtz's Electrodynamics 354 6. Instability in the Fechner-Weber Theory 356 7. Hertz's First Use of the General Helmholtz Equations 358 8. Hertz on the Induction of Polarization by Motion 361 9. Hertz on Relatively Moving, Charged Conductors 364 10. Elastic Bodies Pressed Together 366 11. Evaporation's Theoretical Limits 369 12. Hertz's Model for Geissler-Tube Discharge 372 13. Propagation in Helmholtz's Electrodynamics 375 14. Forces in Hertz's Early Experiments 389 15. Hertz's Quasi Field Theory for Narrow Cylindrical Wires 393 16. Considerations regarding the Possible Background to Helmholtz's New Physics 395 17. Poincare and Bertrand 405 18. Difficulties with Charge and Polarization 407 Notes 415 Bibliography 465 Index 479 • • • FIGURES 1. Herwig's apparatus 17 2. Vertical coil 29 3. Horizontal coil 30 4. Wagner hammer 30 5. Helmholtz interrupter 31 6. Ring magnet and circular capacitor 32 7. Cylindrical electromagnet and circular capacitor 33 8. Schiller's experiment 34 9. A Holtz electrostatic generator 35 10. Helmholtzian induction by Gleitstelle 37 11. Rotating capacitor 39 12. Heinrich Hertz's family tree 46 13. Heinrich Hertz 53 14. Hertz's spirals and bridge 65 15. Hertz's commutator 67 16. Detail of the commutator switch 67 17. Double-wound spiral 69 18. Hertz's experiment diagram 70 19. One spiral out of circuit 70 20. Both spirals in circuit 71 21. Spiral replaced with rectilinear circuit 73 22. Hertz's inductive stimulator 80 23. Couplings in the stimulator 80 24. Action on a linear element 82 25. Setup in fig. 24 seen from above 82 26. Action on a circular element 84 27. Hertz's apparatus for detecting rotational effects 86 28. Rotating dielectric disk 91 29. Representation of current flow lines from Hertz's doctoral dissertation 98 30. Helmholtzian interactions realized 102 31. A sample of Kirchoff's corrections 108 32. Hertz's original 109 viii FIGURES 33. Vapor-pressure curve 115 34. Hertz's evaporation system 116 35. Hertz's first evaporation device 118 36. First redesign of the evaporation device 120 37. The second mutation of the evaporation device 123 38. The emended paragraph 126 39. Excerpt from Hertz's manuscript on Geissler-tube discharge 132 40. The discharge tube as reproduced by J. J. Thomson from an article by E. Wiedemann 134 41. Goldstein's illustration showing cathode rays diverging from the path between electrodes 139 42. Circuit diagram for de la Rue and Muller's intermittence detector 144 43. De la Rue and Muller's intermittence detector 145 44. Hertz's bridge for testing intermittence 149 45. Device to find a nonelectromagnetic action by rays on a magnet 152 46. Apparatus for tracing the current lines 155 47. Hertz's current map 156 48. Hertz's ray purifier 159 49. Purifier electrodes 160 50. Hertz's ray purifier 164 51. Perrin's charge-detection device 164 52. Ray displacement 173 53. Boltzmann's capacity device 210 54. Boltzmann's Leyden jars 211 55. Boltzmann's charge alternator 213 56. The Riess, or Knochenhauer, spiral 219 57. Transformation of the spiral into a linear device 220 58. Probing the potential along the discharge circuit with a Riess micrometer 221 59. Bridging the Riess micrometer with a metallic shunt 222 60. Hertz's diagram for demonstrating that resistance does not account for the device's behavior 223 61. Reflections in the Nebenkreis 226 62. Exploring induction effects with a detached Nebenkreis 229 63. The spark-switched oscillator with detached Nebenkreis 232 64. Manipulating harmonics 237 65. The original device with a gap between k and h 242 66. The original device modified by a dielectric bridging the gap 243 FIGURES ix 67. Hertz's depiction of the direction of the force near the oscillator 250 68. Hertz's conjectured force curve 251 69. Representation of Hertz's account of the forces that act on the resonator 253 70. Apparatus for detecting the effect of neighboring conductors on sparking 258 71. Hertz's apparatus for detecting dielectric induction 260 72. Hertz's diagram for mapping wire waves with the resonator 268 73. Hertz's published diagram for his interference experiments 271 74. Hertz's understanding of the resonator's response 272 75. The critical arrangement 290 76. Hertz's diagram for regions where the force directions cannot be determined 296 77. Hertz's direct measurement of a standing air wave 308 78. Hertz's mathematical dipole 312 79. Hertz's field maps 315 80. A Hertzian nomograph for constant speeds 317 81. Hertz's nomograph 319 82. Possible forms of wire waves 323 83. Hertz's electromechanical model for Geissler-tube discharge 373 84. Hertz's resonator, wire, and oscillator 390 85. Spark curves for interfering metal and air waves with different retardations 391 • • • TABLES 1. Chart of interactions 22 2. An ideal scheme for wire-wave sparking in the case of infinite air speed 274 3. Hertz's marks for December 22 282 4. Hertz's marks for December 23 285 5. Hertz's table establishing finite propagation for the direct electrodynamic action 291 6. Experiments to examine the interference between the static and dynamic actions 293 7. Hertz's final table 294 8. The sequence of Hertz's dipole experiments 297 • • • PREFACE In the late spring of 1988 I decided to write a brief article on a peculiar early deduction of "Maxwell's equations" that was produced in 1884 by Heinrich Hertz, later famed for his production of electric waves. I was at the time lectur­ ing at the University of Copenhagen, where I had been invited by their histo­ rian of mathematics, Jesper Lutzen. His perceptively puzzled questions in re­ sponse to my attempted explanations of Hertz's odd deductions eventually forced me to realize that something quite deep underlay them, something that spoke to Hertz's own puzzlement concerning central, but essentially unstated, points in the physics of his day. This book resulted from that realization, and it is, in part, an extended attempt to work through what I came to see as themes that guided Hertz's work throughout his tragically short career. Although my previous two books, especially the second, had paid some at­ tention to experiment, I had there used the laboratory mostly to explore con­ ceptual structures that were bound to the work that was done within it. So, for example, in discussing Fresnel's diffraction experiments in my second book, or the discovery of the Hall effect in my first, I had been concerned rather with what they had to say about Fresnel's developing understanding of waves or about conceptions of fields than with the experimental work per se. The story I tell here is considerably different, because it concentrates directly upon Hertz's wide-ranging experimental work for its own sake and not for its exemplifica­ tion of something else. "Something else" is nevertheless quite markedly present in Hertz's labora­ tory, but it is not precisely the same kind of thing that informed Fresnel's or even Hall's experimenting. Both of them set out to find something that they had reasonably precise theoretical grounds for believing in or at least for sus­ pecting.