LIST OF ILLUSTRATIONS. 
Plates 1 and 2. —Mr. J. J. Waterston on the Physics of Media that are Composed 
of Free and Perfectly Elastic Molecules in a State of Motion. 
Plates 3 to f>.—Mr. G. J. Burch on the Time-relations of the Excursions of the 
Capillary Electrometer, with a Description of the Method of Using it for the 
Investigation of Electrical Changes of Short Duration. 
Plate 7. —Drs. W. Ramsay and S. Young on some of the Properties of Water and of 
Steam. 
Plates 8 and 9. —Professor W. G. Adams on a Comparison of Simultaneous Magnetic 
Disturbances at Several Observatories. 
Plate 10.—Professor A. M. Worthington on the Mechanical Stretching of Liquids : 
an Experimental Determination of the Volume-Extensibility of Ethyl-Alcohol. 
Plates 11 to 15. —Messrs. W. E. Ayrton and H. Kilgour on the Thermal Emissivity 
of Thin Wires in Air. 
Plate 16.--Messrs. R. T. Glazebrook and S. Skinner on the Clark Cell as a 
Standard of Electromotive Force. 
