viii CONTENTS. 



CHAPTER XI. Gravitational Experiments. 



PAGE 



100. Slender needles 131 



101. Experiments with slender needles 132 



102. Torque exerted on the stem 135 



103. Contemporaneous experiments 136 



104. Filamentary needle 137 



105. Observations 139 



106. The residual radiation forces 139 



CHAPTER XII. Miscellaneous Experiments. 



I. Heavy Gravitational Systems. 



107. Attractions in case of a heavy needle 141 



108. Apparatus 141 



109. Observations 142 



II. The Torsional Magnetic Energy Absorption of an Iron Conductor. 



1 10. Apparatus 144 



in. Observations 144 



112. Data 145 



1 13. Longitudinal field 145 



III. Liquid Refraction Near a Solid Surface. 



114. Methods and first experiment 146 



1 15. Second experiment 147 



IV. Comparison of Two Independent Sets of Fringes. 



1 16. Apparatus 148 



