CONTENTS. 



PAGE 



The Cooling of a Solid Sphere with a Concentric Core of a Different 

 Material. By Professor H. S. Carslaw. (With Three figures in 

 Text) 399 



Symbolical methods in the theory of Conduction of Heat. By Dr T. J. I'a, 



Bromwich, F.R.S. (With Two figures in Text) . . . . 411 



On the effect of a magnetic field on the intensity of spectrum lines. By 

 H. P. Waran, M.A., Government of India Scholar of the Univer- 

 sity of Madras. (Communicated by Professor Sir Ernest Ritther- 

 FORD, F.R.S.) (With Three figures in Text and Plate III) . . 428 



On a property of focal conies and of bicircular quartics. By C. V. Hanu- 

 manta Rao, University Professor, Lahore. (Communicated by 

 Professor H. F. Baker) . , , . . . . . . 434 



Convex Solids in Higher Space. By Dr W. Burnside, Honorary Fellow 



of Pembroke College ........ 437 



Note on the Velocity of X-ray Electrons. By R. WHrDDiNGTON, M.A. 



(With One figure in Text) . • . . . , . , 442 



A Laboratory Valve method for determining the Specific Inductive 

 Capacities of Liquids. By R. Whiddington, M.A. (With One 

 figure in Text) ••....... 445 



The Theoretical Value of Sutherland's Constant in the Kinetic Theory of 

 Oases. By C. G. F. James, Trinity College, Cambridge. (Communi- 

 cated by Mr R. H. Fowler.) (With One figure in Text) . . 447- 



On the Stability of the Steady Motion of viscous liquid contained between 

 two rotating coaxal circular cylinders. By W. J. Harrison, M.A., 

 Fellow of Clare College, Cambridge . . . . . . 455 



The soaring flight of dragon-flies. By E. H. Hankin, M.A., Sc.D., Agra, 



India. (With Three figures in Text) 460 



The Gluteal Region of Tarsius spectrum. By A. B. Appleton (With 



Plate IV) '. . 466 



An unusual type of male secondary characters in the Dipt era. By C. G. 



Lamb, -M.A. (With Four figures in Text) ..... 475 



A Note on the Mouth-parts of certain Decapod Crustaceans. By L. A. 

 BoRRADAiLE, M. A., FeUow and Tutor of Selwyn College, Cambridge, 

 and Lecturer in Zoology in the University. .... 478 



An Apparatus for Projecting Spectra. By H. Haetridge . . . 480 



Note on true and apparent hermaphroditism in sea-urchins. By J. Gray, 



M.A., Balfour Student, Cambridge University .... 481 



On Certain Simply-Transitive Permutation-Groups. By Dr W. Burn- 

 side, Honorary Fellow of Pembroke College .... 482 



Proceedings at the Meetings held during the Session 1920—1921 . 485 



Index to the Proceedings with references to the Transactions . . 492 



