CONTENTS of N° 230.— Fourth Series. 



XXXIII. On the Water of the River Severn at Worcester. By 

 Augustus Beauchamp Northcote, M.A., F.C.S., late Radcliffe Fel- 

 low in the University of Oxford page 249 



XXXIV. On a Resistance-measurer. By C. W. Siemens, F.R.S. 270 



XXXV. On the Source of Muscular Force. By John Douglas, 

 East-India Government Telegraph Department 273 



XXXVI. Theory of the Evening Glow and analogous Phenomena. 



By Dr. E. Lommel 275 



XXXVII. On the Approximate Drawing of Circular Arcs of given 

 Lengths. By W. J. Macquorn Rankine, C.E., LL.D., F.R.S 284 



XXXVIII. On the Identity of the Vibrations of Light with Elec- 

 trical Currents. By L. Lorenz 287 



XXXIX. On the Spectrum of the Bessemer-flame. By Professor 

 Lielegg 302 



XL. Proceedings of Learned Societies : — 



Royal Society: — Mr. G. J. Stoney on the Physical Constitu- 

 tion of the Sun and Stars ; Prof. H.E. Roscoe on the Chemical 

 Intensity of Total Daylight at Kew and Para in 1865-67 ; Dr. 

 T. Andrews on the Identity of the Body in the Atmosphere 

 which decomposes Iodide of Potassium with Ozone 304-3 1 6 



Geological Society: — Mr. R. Etheridge on the Physical 

 Structure of North Devon ; Sir W. E. Logan on new Speci- 

 mens of Eozoon ; Dr. Dawson on Fossils recently obtained 

 from the Laurentian Rocks of Canada ; Mr. W. Whitaker on 

 Subaerial Denudation ; Captain T. A. B. Spratt on the Bone- 

 caves in the Island of Malta ; Mr. R. Tate on the Lower Lias 

 of the North-east of Ireland, and on the Fossiliferous Deve- 

 lopment of the zone of Ammonites angulatus in Great Britain ; 

 Mr. F, M. Burton on the Rhsetic Beds near Gainsborough. 317-322 

 XLI. Intelligence and Miscellaneous Articles: — 



Note on the Electrical Condition of the Terrestrial Globe, by A. 

 De la Rive 322 



On Brewster's Neutral Point, by Pliny Earle Chase .-..". 325 



Note on the Force which the Muscle of a Frog can develope in 

 Contracting, by M. J. Rosenthal 325 



Investigations on the Absorption of Obscure Heat, by M. P. 

 Desains 327 



On the Change of Obliquity as a cause of Change of Climate, by 

 J. Carrick Moore 328 



%* It is requested that all Communications for this Work may be addressed, 

 post-paid, to the Care of Messrs. Taylor and Francis, Printing Office, Red 

 Lion Court, Fleet Street, London. 



