[ ii' ] 
CONTENTS. 
1 
VOL. 212. 
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. page V 
I. Bakerian Lecture. — On the Variation of the Specific Heat of Water, with 
Experiments hy a New Method. By H. L. Callendar, M.A., LL.D., F.R.S., 
Professor of Physics at the Impericd College of Science and Technology, 
London, ^S'. TV..1 
II. A Critical Study of Spectral Series. — Pao^t II. The p) and s Se<piences and the 
Atomic Volume Term. By W. M. Hicks, Sc.D., F.R.S. .33 
III. Some Phenomena of Sunspots and of Terrestricd Magnetism at Keiv Obser¬ 
vatory. By C. Chree, Sc.D., LL.D, F.R.S., Sujjerintendent of Kew 
Observatory ..75 
IV. Physico-Chemical Determinations at High Pressures by Optical Methods. 
[Research executed in the Davy Faraday Research Laboratory of the Royal 
Institution of Great Britcdn, London, TT^.) By Walter Wahl, Ph.D., 
Rosenberg Research Fellow of the Unive'rsity of Helsingfors. Communicated 
by Sir James Dewar, F.R.S. .117 
V. A New Treatment of Opticcd Aberrations. By R. A. Sampson, F.R.S. . 
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