ERRATUM IN VOL. XXVI. 

 Page 511, for y=Y)d, read y=Dd*. 



ERRATA IN VOL. XXVII. 



Throughout Plate 4 the letter x ought to match in size the letter «. 



Page 78, lines 13 and 27, and page 79, line 16, for Greenwich-Kew read 

 Kew-Greenwich. 



Page 119, line 8 for hypochloric read hydrochloric. 



