PLATES. 



I. Illustrative of Prof. J. Perry's Paper on a Table of Zonal Spherical 



Harmonics. 



II. Illustrative of Prof. C. A. Cams Wilson's Paper on the Influence 



of Surface-Loading on the Flexure of Beams. 



III. & IV. Illustrative of Dr. A. Richardson's Paper on the Expansion 

 of Chlorine by Light as applied to the Measurement of the 

 Intensity of Rays of High Refrangibility. 



V-. Illustrative of Mr. A. P. Chattock's Paper on the Electrification 

 of Steel Needle-Points in Air. 



ERRATA. 



Page 27, line 8 from bottom, for incredible read inscrutable. 

 „ 438, top line, insert t' between " -when " and " is." 



