CONTENTS OF VOL. XLIII. 



(SIXTH SEKIES). 



71U_ 



NUMBER CCLIII.— JANUARY 1922. 



Page 

 Prof. J. W. Nicholson on Zonal Harmonics of the Second Type . . 1 

 Prof. F. I). Muvnaghan on the Derivation of Symmetrical Gravita- 

 tional Fields 19 



Profs, J. N. Bro asted and G. Hevesy on the Separation of the 



Isotopes of Mercury 31 



Mr. A. R. McLeod on the Lags of Thermometers 49 



Dr. T. J. I'a. Bromwich on Kinetic Stability • 70 



Mr. V. Lough on the Beating Tones of Overblown Organ Pipes. 



(Plate I.) 72 



Messrs. C. N. Hinshelwood and II. Hartley on the Probability of 



Spontaneous Crystallization of Super-cooled Liquids 78 



Mr. J. J. Mauley on the Insulation of Highly Attenuated Wires in 



Platinum Resistance Thermometers , 95 



Dr. John Prescott on the Equations of Equilibrium of an Elastic 



Plate under Normal Pressure „ 97 



Prof. S. P. Timoshenko on the Transverse Vibrations of Bars of 



Uniform Cross-Section 125 



Prof. A. Anderson on Scalar and Vector Potentials due to Moving 



Electric Charges , . . . 131 



Prof. 0. W. Richardson on Gravitation. With an Appendix by 



Dr. L. Simons 138 



Prof. A. LI. Hughes on Characteristic X-Rays from Boron and 



Carbon 145 



Prof. 0. W. Richardson and Mr. F. S. Robertson on the Effect of 

 Gases on the Contact Difference of Potential between Metals at 



Different Temperatures 162 



Pro!'. A. S. Eddington on the significance of Einstein's Gravita- 

 tional Equations in terms of the Curvature of the World 174 



Mr. E. V. Appleton and Dr. Balth. van der Pol on a Type of 



Oscillation-Hysteresis in a Simple Triode Generator 177 



Mr. S. Ratner on Polarization Phenomena in X-Ray Bulbs 193 



Messrs. A. F. Joffe and M. V. Kirpitcheva on Rontgenograms of 



Strained Crystals. (Plate II.) 204 



Dr. Alfred A. Robb on a Graphical Solution of a Class of Differen- 

 tial Equations occurring in Wireless Telegraphy ; with Note bv 



Mr. E. V. Appleton 206 



Profs. D. N. Mallik and A. B. Das on certain Types of Electric 



Discharge 2 16 



Mr. W. Sucksmith on the Application of the Ultra-Micrometer to 



the Measurement of Small Increments of Temperature 223 



Mr. H. P. Waran on an Interesting Case of Mechanical Disintegra- 

 tion caused by Positive Ions 226 



Dr. Leonard B. Loeb on the Relative Affinity of some Gas Mole- 

 cules for Electrons 229 



