CONTENTS. 
PART I. 
I. On the Determination of the Rate of Vibration of Tuning-Forks. By Herbert 
M‘Leod, F.C.S., and George Sydenham Clarke, Lieut. R.E., Royal Indian 
Engineering College, Coopers Hill. Communicated by Lord Rayleigh, M.A., 
F.R.S .page 1 
II. The Contact Theory of Voltaic Action .—Paper No. III. By Professors W. E. 
Ayrton and John Perry. Communicated by Dr. C. W. Siemens, F.R.S. 15 
III. Researches on the Comparative Structure of the Cortex Cerebri. By W. Beyan 
Lewis, L.R.C.P. ( Bond.), Senior Assistant Medical Officer, West Riding 
Lunatic Asylum, Wakefield. Communicated by Dr. Ferrier, F.R.S., Pro¬ 
fessor of Forensic Medicine, King's College, London . 35 
IX. Experimental Researches on the Electric Discharge with the Chloride of Silver 
Battery. By Warren De La Rue, M.A., D.C.L., F.R.S., and Hugo W. 
Muller, Ph.D., F.R.S .—Part III. Tube-Potential; Potential at a Constant 
Distance and Various Pressures; Nature and Phenomena of the Electric 
Arc . 65 
V. On the Conduction of Heat in Ellipsoids of Revolution. By C. Niven, M.A., 
Professor of Mathematics in Queens College, Cork. Communicated by J. W. L. 
Glaisher, F.R.S. . 117 
YI. On some recent Improvements made in the Mountings of the Telescopes at Birr 
Castle. By the Earl of Rosse, F.R.S. . 153 
VII. Concluding Observations on the Locomotor System of Medusce. By George J. 
Romanes, M.A., F.L.S. Communicated by Professor T. H. Huxley, IjL.D., 
Sec. R.S . 161 
YIII. Researches on Explosives .-— No. II. Fired Gunpowder. By Captain Noble 
(late R.A.), F.R.S., F.R.A.S., F.C.S., &c., and F. A. Abel, C.B., F.R.S., 
V.P.C.S., &c., &c .203 
