LIST OF ILLUSTRATIONS. 
Plate 1.—Dr. A. Schuster on the Spectra of Metalloids. 
Plates 2 to 13.—Sir William Thomson on the Electrodynamic Qualities of Metals. 
Plate 14.— Mr. W. Crookes on the Illumination of Lines of Molecular Pressure, and 
the Trajectory of Molecules. 
Plates 15 to 20.— Messrs. W. Spottiswoode and J. Fletcher Moulton on Electrical 
Discharges through Rarefied Gases. 
Plates 21 to 34.— Messrs. W. N. Hartley and A. K. FIuntington on the Action of 
Organic Substances on the Ultra-violet Rays of the Spectrum. 
Plate 35.— Mr. J. B. Hannay on the Microrheometer. 
Plate 36. —Mr. G. H. Darwin on the Precession of a Viscous Spheroid, and on the 
remote History of the Earth. 
Plates 37 to 45.—Mr. W. K. Parker on the Structure and Development of the Skull 
in the Lacertilia. 
Plate 46.— Professor Prestwick on the Oriafin of the Parallel Roads of Lochaber. 
Plates 47 to 49. —Professor O. Reynolds on certain Dimensional Properties of Matter 
in the Gaseous State. 
