ADDITIONS AND CORRECTIONS. 
Page 99, line 5, for Protagoras, read Protogenes 
186, last line, for southerly, read northerly 
204, line 4 ,for heat, read iodine 
272, line 17, for about io*, read between iz° and 14* 
275, line 18, for 39 0 , read 3 7 0 30' 
277, line 17, for nearly read less than 
Id. lines 21 and 23, for 141 0 , read 141 0 53' 
278, line 12, at the word crystallized, insert the following as a note: The 
interrupting stratum is crystallized in a different manner from the rest of the rhom- 
boid. The position of its axes with respect to those of the rhomboid, and the singu- 
lar optical phenomena which arise from this cause, will be described in another paper. 
288, Note, line 4, for parallel read perpendicular 
