PLATES IN VOL. X. (New Series.) 



Plates Page 



XXXVL— Dr. Roget on an Optical Deception 108 



XXXVIL — Improved Air-pump 362 



ERRATA. 



Page 46, for 30 inches, read 29-92181 inches. 



123, line 13, /or fluoric add, read fluoboric acid. 



124, line 12, for neutral, read mutual. 

 152, line 5, /or analysis, read analyses. 



