PLATES. 
I, Illustrative of Mr. Walter Baily's Paper on the Crossing of Rays. 
II. Illustrative of Professors Ayrton and Perry's Paper on the Mea- 
surement of the Electric Resistance of Liquids. 
III. Illustrative of Mr. L. Fletcher's Paper on the Dilatation of Crys- 
tals on Change of Temperature. 
IV. & V. Illustrative of Frederick Guthrie's Paper on certain Molecular 
Constants. 
VI. Illustrative of Professors Liveing and Dewar's Paper on Sun-spots 
and Terrestrial Elements in the Sun. 
VII. Illustrative of Messrs. Galloway and O'Farrell's Paper on some 
Improved Laboratory Appliances for conducting mauy Chemical 
Operations at the same time, and hastening the completion of 
several of them, 
VIII. Illustrative of Messrs. Mills and Mackey's Paper on Lines of no 
Chemical Change. 
