[ iii ] 
CONTENTS. 
(A) 
VOL. 220. 
List of Illustrations . . .page v 
Advertisement. vii 
I. Tidal Friction in the Irish Sea. By G. I. Taylor, M.A. Communicated by 
Sir Napier Shaw, F.R.S. . page 1 
II. Electromagnetic Integrals. By Sir G. Greenhill, F.R.S . 35 
III. Bakerian Lecture, 1918. —Experiments on the Artificial Production of 
Diamond. By the Hon. Sir Charles Algernon Parsons, K.C.B., 
F.R.S. . 67 
IV. The Pressure upon the Poles of the Electric Arc. By W. G. Duffield, D.Sc., 
Professor of Physics, Captain, Royal Air Force, Thos. H. Burnham, B.Sc., 
and A. H. Davis, B.Sc., Post-Graduate Students in Physics, University 
College, Reading. Communicated by Prof O. W. Richardson, F.R.S. . 109 
V. On Intensity Relations in the Spectrum of Helium. By T. R. Merton, D.Sc., 
Lecturer in Spectroscopy, University of London, King's College, and 
J. W. Nicholson, F.R.S., Professor of Mathematics in the University of 
London . 137 
VI. The Scattering of Plane Electric Waves by Spheres. By T. J. I’A. Bromwich, 
Sc.D., F.R.S. .175 
