PROCEEDINGS OF 

 THE ROYAL SOCIETY. 



VOL. XV. No. 81. 



CONTENTS. 



Fehruwry 1, 1866. 



PAGE. 



I, On the Specific Gravity of Mercury. By Balfotje Stewaet, M.A., LL.D., 



F.R.S., Superintendent of the Kew Observatory 10 



II. On the Forms of Graphitoidal Silicon and Graphitoidal Boron. By W. 

 H. MiLLEE, M.A., For. Sec. E.S., and Professor of Mineralogy in the 

 University of Cambridge 11 



Felrucmf 8, 1866. 



On the Viscosity or Internal Friction of Air and other Gases, being the 

 Bazeeian Lectuee, dehvered by James Cleek Maxwell, M.A., F.R.S. 14 



Felruary 15, 1866. 

 Further Observations on the Spectra of some of the Nebulse, ^th a Mode of 



determining the Brightness of these Bodies. By William Huggins, 

 F.E.S. . 17 



February 22, 1866. 



I. Account of Experiments on the Flexural and Torsional Eigidity of a Glass 



Bod, leading to the determination of the Eigidity of Glass. By J OSEPH D. 

 EvEEETT, D.C.L., Assistant to the Professor of Mathematics in the Uni- 

 versity of Glasgow 19 



II. Note on the relative Chemical Intensities of direct Sunlight and diffuse Day- 



light at different Altitudes of the Sun. By Henby E. Eoscoe, F.E.S., and 

 Joseph Baxendell, F.E.A.S. (Plate I.) . 20 



TAYLOE AND FEANCIS, EED LION COUET, FLEET STEEET. 



