ERRATA. 



p. 71, 1. 3 from bot. for stone read stove. — p. 75, 1. 21 from bot. for their read tliese 

 1. 17 from bot. for 11th read I2th and insert a, before geometrical. — p. 84 1. 12 from 

 bot. for 100 "down to 18" read 100" down to 18"— p. 85, in the table against mean 

 in the 5th series, for 226 read 266. 



ALTERATIONS FROM COPY. 



p. 76, line 5 fr. top, omit the words axis of the. — p. 81, 1. 3 fr. bot. add — The first 

 six experiments are projected in the order of their magnitudes, beginning with the 

 greatest, though this was not precisely that of their occurrence, as will be seen by 

 recurring to the commencement of the 8th series in the table. 



p. 136, 1. 24 from top, after C. quadrigeminum, read C. hexagonum; same page, 

 1. 25 from top, for six read seven. — p. 137, 1. 26 fr. top, for Catenipora auleticon, read 

 escharoides; same page, 1. 22 fr. top, place Sarcinula auleticon, after T. affinis? in 

 "the last line before the note on p. 136. 



