vii 



Page 



Meeting of May 23, 1901, and List of Papers read 262 



On Negative After-images, and their Relation to certain other Visual 

 Phenomena. By Shelf ord Bidwell, M.A., Sc.D., F.R.S 262 



The Solar Activity, 1833-1900. By William J. S. Lockyer, ML A., 

 PhD., F.R.A.S., Assistant Director, Solar Physics Observatory, 

 Kensington. Communicated by Sir Norman Lockyer, K.C.B., 

 F.R.S 285 



No. 447. 



On the Variation in Gradation of a Developed Photographic Image 

 when impressed bv Monochromatic Light of Different Wave-lengths. 

 By Sir William de W. Abney, K.C.B., D.C.L., D.Sc, F.R.S 300 



A Comparative Crystallographical Study of the Double Selenates of 

 the Series R 2 M(Se0 4 ) 9 ,6H 2 0— Salts in which M is Magnesium. By 

 A. E. Tutton, B.Sc, F.R.S 322 



On the Presence of a Glycolytic Enzyme in Muscle. By Sir T. Lauder 



Brunton, M.D., F.R.S., and Herbert Rhodes, M.B 323 



Annual Meeting for the Election of Fellows 326 



Meeting of June 6, 1901, and List of Papers read 327 



Vibrations of Rifle Barrels. By A. Mallock. Communicated by Lord 

 Rayleigh, F.R.S 327 



A Conjugating " Yeast." By B. T. P. Barker, B.A., Gonville and Caius 

 College, Cambridge. Communicated by Professor Marshall Ward, 

 F.R.S , 345 



The Measurement of Magnetic Hysteresis. By G. F. C. Searle, M.A., 

 and T. G. Bedford, M.A. Communicated by Professor J. J. 

 Thomson, F.R.S 348 



Thermal Adjustment and Respiratory Exchange in Monotremes and 

 Marsupials. — A Study in the Development of Homothermism. By 

 C. J. Martin, M.B., D.Sc, Acting Professor of Physiology in the 

 University of Melbourne. Communicated by Professor E. H. 

 Starling, F.R.S 352 



On the Elastic Equilibrium of Circular Cylinders under certain Practical 

 Systems of Load. By L. N. G. Filon, M.A., B.Sc, Research Student 

 of King's College, Cambridge ; Fellow of University College, 

 London ; 1851 Exhibition Science Research Scholar. Communi- 

 cated by Professor Ewing, F.R.S 353 



The Measurement of Tonic Velocities in Aqueous Solution, and the 

 Existence of Complex Ions. By B. D. Steele, B.Sc, 1851 Exhibition 

 Scholar (Melbourne). Communicated by Professor Ramsay, F.R.S... 358 



No. 448. 



Meeting of June 13, 1901 360 



Bakerian Lecture.— The Nadir of Temperature, and Allied Problems. 

 1. Physical Properties of Liquid and Solid Hydrogen. 2. Separation 



