RECENT PAPERS IN THE ‘PHILOSOPHICAL TRANSACTIONS,’ 
1917-19. 
A 555. 
A 556. 
A 557. 
A 558. 
A 559. 
A 560. 
A 561. 
A 562. 
B 352. 
B 353. 
B 354. 
B 355. 
B 356. 
B 357. 
B 358. 
B 359. 
Series A.—Mathematical and Physical. 
On Phenomena Relating to the Spectra of Hydrogen and Helium. By T. R. Merton, D.Sc. 
(Oxon), Lecturer in Spectroscopy, University of London, King’s College, and J. W. Nicholson, 
M.A., D.Sc., Professor of Mathematics in the University of London. Pp. 42; 2 Plates. 
Price 2s. 6 d. 
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. Pp. 36. 
Price 3s. 
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 Pp. 46. Price 3s. 
A Critical Study of Spectral Series. Part IV.—The Structure of Spark Spectra. By 
W. M. Hicks, F.R.S. Pp. 50; 15 Plates. Price 3s. 6 d. 
On the Photographic Spectra of Meteorites. By Sir William Crookes, O.M., F.R.S., LL.D., 
D.Sc., &c. Pp. 20; 2 Plates. Price 3s. 6 d. 
Title, Contents, Index, &c., Vol. 217. Pp. 10. Price 6 d. 
The Solar and Lunar Diurnal Variations of Terrestrial Magnetism. By S. Chapman, M.A., 
D.Sc., Fellow and Lecturer of Trinity College, Cambridge, and Chief Assistant at the Royal 
Observatory, Greenwich. Pp. 118. Price 7s. 6d. 
The Specific Heat of Aqueous Solutions, with Special Reference to Sodium and Potassium 
Chlorides. By W. R. Bouseteld, M.A., K.C., F.R.S., and C. Elspeth Bousfield. Pp. 38. 
Price 3s. 
Series B. — Biological. 
Analyses of Agricultural Yield. Part III.—The Influence of Natural Environmental Factor* 
upon the Yield of Egyptian Cotton. By W. Lawrence Balls, Sc.D., late Fellow of 
St. John’s College, Cambridge. Pp. 67. Price 5s. 
An Investigation into the Periodicity of Measles Epidemics in London from 1703 to the Present 
Day by the Method of the Periodogram. By John Brownlee, M.D., D.Sc. Pp. 26. 
Price 2s. 
On the Structure and Development of the Tubular Enamel of the Sparidae and Labrida. By 
J. Howard Mummery, D.Sc. (Hon.), Penn., M.R.C.S. Pp. 19; 2 Plates. Price 2s. 
The Cytomorphosis of the Marsupial Enamel-Organ and its Significance in Relation to the 
Structure of the Completed Enamel. By J. Thornton Carter. Pp. 35; 4 Plates. 
Price 5s. _ \ ' 
The Development of the Pancreas, the Pancreatic and Hepatic Duets, in Trichosurus Vulpecula. 
By Margaret Tribe, M.Sc. (Lond.), Percy Macgregor Research Scholar. Pp. 44 ; 1 Plate. 
Price 5s. 
The Fossil Human Skull found at Talgai, Queensland. By Stewart Arthur Smith, M.B., 
Ch.M. Pp. 37 ; 7 Plates. Price 5s. 
New Bennettitean Cones from the British Cretaceous. By Marie C. Stopes, D.Sc. (Lond.), 
Ph.D. (Munich), Fellow and Lecturer iu Palaeobotany, University College, London. Pp. 52; 
6 Plates. Price 10s. 
Title, Contents, Index, &c., Vol. 208. Pp. 10. Price 6 d. 
Cloth cases for binding the volumes of the ‘ Philosophical Transactions.’ Price 2s. 6 d. 
Published for the ROYAL SOCIETY by 
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