CONTENTS 
OF VOL. 150. 
I. On the Analytical Theory of the Attraction of Solids bounded by surfaces of a hypo- 
thetical Class including the Ellipsoid. EyW. F. Donkin, M.A., F.R.S., F.B..A.S., 
Savilian Professor of Astronomy in the University of Oxford .... page 1 
II. On an Extended Form of the Index Symbol in the Calculus of Operations. By Wil- 
liam Spottiswoode, M.A., F.B.S 13 
III. On the Besin of Ficus mbiginosa, and a new Ilomologue of Benzylic Alcohol. By 
Waeren De la Eue, Ph.D., F.B.S., Treasurer of the Chemical Society, Secretary 
of the Boyal Astronomical Society, &c., and Hugo Muller, Ph.D., F.C.S. . 43 
IV. On the Theory of Compound Colours, and the Relations of the Colours of the 
Spectrum. By J. Clerk Maxwell, M.A., Professor of Natural Philosophy in 
Marischal College and University of Aberdeen. Communicated by Professor Stokes, 
Sec.B.S. ' 57 
V. On the Effect of the presence of Metals and Metalloids upon the Electric Conducting 
Power of Pure Copper. By A. Matthiessen, Ph.D., and M. Holzmann, Ph.D. 
Communicated by Professor Wheatstone, F.B.S. 85 
VI. On the Equation of Differences for an Equation of any Order, and in particular for 
the Equations of the Orders Two, Three, Four, and Five. Bn Arthur Cayley, 
Esq., F.B.S 93 
VII. On the Volumetric Relations of Ozone, and the Action of the Electrical Discharge 
on Oxygen and other Gases. By Thomas Andrews, M.D., F.B.S., M.B.I.A., 
Vice-President of Queens College, Belfast ; and Peter G. Tait, M.A., late Fellow 
of St. Peter s College, Cambridge, Professor of Mathematics in Queens College, 
Belfast 113 
VIII. On the Mathematical Theory of Sound. By the Rev. S. Earnshaw, M.A., Shef- 
field. Communicated by Professor N. H. Miller, F.B.S 133 
