[ iv ] 
VII. On Phenomena Relating to the Spectra of Hydrogen and Helium. By T. R. 
Merton, D.Sc. ( Oxon), Lecturer in Spectroscopy , University of London, 
Kings College, and J. W. Nicholson, M.A., D.Sc., Professor of Mathe¬ 
matics in the University of London. Communicated by Prof. A. Fowler, 
F.R.S. ... page 237 
VIII. Numerical Results of the Theory of the Diffraction of a Plane Electromagnetic 
Wave by a Perfectly Conducting Sphere. By J. Proudman, A. T. Doodson 
and G. Kennedy. Communicated by T. J. I’A. Bromwich, Sc.D., 
F.R.S. . 279 
IX. Bakerian Lecture. —On X-rays and the Theory of Radiation. By C. G. 
Barkla, F.R.S., Professor of Natural Philosophy in the University of 
Edinburgh . . 315 
X. A Critical Study of Spectral Series.—Part IV. The Structure of Spark 
Spectra. By W. M. Hicks, F.R.S. . 361 
XI. On the Photographic Spectra of Meteorites. By Sir William Crookes, O.M., 
F.R.S., LL.D., D.Sc., &c . 411 
Index to Volume . 431 
4 
