vii 



Page 



On the Height of the Aurora Borealis. By Warren De La Rue, M.A., 

 D.C.L., F.E.S., and Hugo W. Muller, Ph.D., F.B.S 332 



April 29, 1880. 



Note on the Spectrum of Carbon. By J. Norman Lockyer, F.E.S 335 



On the Diurnal Variation in the Amount of Carbon Dioxide in the Air. 

 By George Frederick Armstrong, M.A., F.G.S., C.E., Professor of 



Engineering in the Yorkshire College, Leeds 343 



Measurement of the Actinism of the Sun's Eays and of Daylight. By 

 Dr. E. Angus Smith, F.R.S 355 



On some Elementary Principles in Animal Mechanics. No. X (conclud- 

 ing the series). Further illustrations of the " Law of Fatigue." By 

 the Eev. Samuel Haughton, M.D. (Dubl.), D.C.L. (Oxon.), F.E.S., 

 Fellow of Trinity College, Dublin 359 



On the Absence of Potassium in Protagon prepared by Dr. Gamgee. By 

 Professor H. E. Roscoe, LL.D., F.R.S 365 



List of Presents 365 



No. 204.— May 13, 1880. 



List of Candidates for Election 373 



Notice of further Experimental Researches on the Time-relations of the 

 Excitatory Process in the Ventricle of the Heart of the Frog. By .J. 

 Burdon-Sanderson, M.D., LL.D., F.R.S., Jodrell Professor of Physio- 

 logy, University College, and F. J. M. Page, B.Sc, F.C.S 373 



On a New Eheotome. By J. Burdon-Sanderson, M.D., LL.D., F.E.S. , 

 Jodrell Professor of Physiology, University College 383 



On the Chemical Composition of Aleurone-Grains. By S. H. Vines, 

 M.A., D.Sc, Fellow of Christ's College, Cambridge 387 



Some Observations upon the Hydrolytic Ferments of the Pancreas and 

 Small Intestine. By Horace T. Brown, F.I.C., F.C.S., and John Heron, 

 F.C.S ; 393 



On the Ova of Echidna hystrix. By Professor Owen, C.B., F.E.S 407 



May 27, 1880. 



On some Thermal Effects of Electric Currents. By William Henry 

 Preece, General Post Office 408 



A. Preliminary Account of the Reduction of Observations on Strained 

 Material, Leyden Jars, and Voltameters. By John Perry and W. E. 

 Ayrton 411 



On the Structure and Development of the Skull in the Batrachia. Part 

 III. By W. K. Parker, F.E.S 435 



