Papers read to the Society, June 20, 1901.

I. “On the Mathematical Theory of Errors of Judgment, with Special Reference to the Personal Equation.” By Professor Karl Pearson, F. R. S. II. “Mathematical Contributions to the Theory of Evolution. X.—Supplement to a Memoir on Skew Variation.” By Professor Karl Pearson, F. R. S. III. “On the Application of Maxwell’s Curves to Three-colour Work, with Especial Reference to the Nature of the Inks to be employed, and to the Determination of the Suitable Light-filters.” By Dr. R. S. Clay. Communicated by Sir W. Abney, K.C.B., F. R. S. IV. “The Nature and Origin of the Poison of Lotus Arabicus .” By W. R. Dunstan, F. R. S., and T. A. Henry. V. “On the Structure and Affinities of Dipteris , with Notes on the Geological History of the Dipteridinse.” By A. C. Seward, F. R. S., and Miss E. Dale. VI. “Further Observations on Nova Persei. No. 3.” By Sir Norman Lockyer, K.C.B., F. R. S. VII. “Total Eclipse of the Sun, May 28, 1900: Account of the Observations made by the Solar Physics Observatory Eclipse Expedition and the Officers and Men of H.M.S. ‘Theseus,’ at Santa Pola, Spain.” By Sir Norman Lockyer, K.C.B., F. R. S. VIII. “The Mechanism of the Electric Arc ” By Mrs. H. Ayrton. Communicated by Professor Perry, F. R. S. IX. “The Yellow Colouring Matters accompanying Chlorophyll and their Spectroscopic Relations. Part 2.” By C. A. Schunck. Communicated by E. Schunck, F. R. S. X. “Magnetic Observations in Egypt, 1883-1901.” By Captain H. G. Lyons. Communicated by Professor Rucker, F. R. S. XI. “A Determination of the Value of the Earth’s Magnetic Field in International Units, and a Comparison of the Results with the Value given by the Kew Observatory Standard Instruments.” By W. Watson, F. R. S. XII. “Virulence of Desiccated Tubercular Sputum.” By H. Swithinbank. Communicated by Sir H. Crichton Browne, F. R. S. XIII. “The Effect of the Temperature of Liquid Air upon the Vitality and Virulence of the Bacillus tuberculosis .” By H. Swithinbank. Communicated by Sir H. Crichton Browne, F. R. S. XIV. “The Fermentation of Urea: a Contribution to the Study of the Chemistry of the Metabolism in Bacteria.” By Dr. W. E. Adeney. Communicated by Professor W. N. Hartley, F. R. S. XV. “On the Seasonal Variation of Atmospheric Temperature in the British Isles and its Relation to Wind-direction, with a Note on the Effect of Sea Temperature on the Seasonal Variation of Air Temperature.” By W. N. Shaw, F. R. S., and R. Waley Cohen. XVI. “On the Continuity of Effect of Light and Electric Radiation on Matter.” By Professor J. C. Bose. Communicated by Lord Rayleigh, F. R. S. XVII. “On the Similarities between Radiation and Mechanical Strains.” By Professor J. C. Bose. Communicated by Lord Rayleigh, F. R. S. XVIII. “On the Strain Theory of Photographic Action.” By J. C. Bose. Communicated by Lord Rayleigh, F. R. S. XIX. “The Anomalous Dispersion of Sodium Vapour.” By Professor R. W. Wood. Communicated by Professor C. V. Boys, F. R. S.. XX. “The Pharmacology of Pseudaconitine and Japaconitine considered in Relation to that of Aconitine.” By Professor J. T. Cash, F. R. S., and Professor W. R. Dunstan, F. R. S. XXI. “The Pharmacology of Pyraconitine and Methylbenzaconine considered in Relation to that of Aconitine. By Professor J. T. Cash, F. R. S., and Professor W. R. Dunstan, F. R. S. XXII. “On the Separation’of the Least Volatile Gases of Atmospheric Air, and their Spectra.” By Professor Liveing, F. R. S., and Professor Dewar, F. R. S. XXIII. “The Stability of a Spherical Nebula.” By J. H. Jeans. Communicated by Professor G. H. Darwin, F. R. S. XXIV. “On the Behaviour of Oxy-hæmoglobin, Carbonic Oxide Hæmoglobin, Methæmoglobin, and certain of their Derivatives, in the Magnetic Field, with a Preliminary Note on the Electrolysis of the Hæmoglobin Compounds.” By Professor Gamgee, F. R. S. XXV. “On the Resistance and Electromotive Forces of the Electric Arc.” By W. Duddell. Communicated by Professor Ayrton, F. R. S. XXVI. “On the Relation between the Electrical Resistances of Pure Metals and their Molecular Constants.” By W. Williams. Communicated by Professor Andrew Gray, F. R. S.