ADDITIONS AND CORRECTIONS. 
• dx djc^ 
Page 135, last line but two, /or <r — , read a — 
dr dr 
^ dy , dy° 
one, for a- — , read o- -j- 
dr dr 
dz dz° 
■ , for cr — , read cr — — 
dr dr 
141, line i,for <r"p° cos. sin. (g®— «), read o-/® cos. x® sin. (c®— «) 
151.- 
(r»-r'»)» , (r^_r'»)» 
(r-fr'*) ' (r+r')’ 
180, — — 9>/or o-y' cos. ?P sin. (c® — n), roorf o^p® cos. x® sin. (c®— «) 
399, line 11, for perfectly, read perfectly flat 
iS,fo^ S, read S' 
22, for s, read s', and for rs, read rs' 
— 402, tabic, col. 3, /or 4® 37', read 3® 37' 
— 403, line 12, for Ms'N^, read Ms'N^' 
— 487, —— 3, at the word iodine, add the following note : I am obliged to 
M. Courtoisfor the iodine employed in these experiments, who, with great 
liberality, furnished me with a considerable quantity. 
