PLATES. 



I. Illustrative of Prof. C. V. Raman and Mr. Ashutosh Dey's Paper 

 on the Maintenance of Vibrations by a Periodic Field of 

 Force. 

 II. & III. Illustrative of Mr. G. A. Hemsalech's Paper on the Origin 

 of the Line Spectrum emitted by Iron Vapour in the Explosion 

 Region of the Air-Coal Gas Flame. 

 IV.-VI. Illustrative of Prof. E. H. Barton and Miss H. M. Browning's 

 Paper on Vibrations under Variable Couplings Quantitatively 

 Elucidated by Simple Experiments. 



