reception for a long series of years. The System 

 of Mr VON LEONHARD is of a later date, and is 

 recommended by its comprehensive references to 

 mineralogical works, and other interesting notices. 

 Among the French works on Mineralogy, those 

 of the Abbe HAUY have been selected, as being 

 most generally received and understood. The 

 nomenclature used in both editions of his Traite de 

 Mineralogie, and in the Tableau Comparatif, may 

 of itself be considered as an abstract of the history of 

 his system. 



The works and memoirs of Messrs BROOKE, 

 LEVY, and PHILLIPS, have been consulted in regard 

 to numerous and highly valuable crystallographic 

 observations on several substances, which had not 

 before been examined with sufficient exactness, and 

 which were unknown to Professor MOHS, at the 

 publication or the composition of the German ori- 

 ginal. 



It was not till the publication of the first vo- 

 lume of this work, in 1822, that the axis of any 

 mineral was ascertained, by actual measurement, 

 to be in an inclined position towards the base: 

 and although that fact, which was first intro- 

 duced into crystallography by Mr MOHS, is 

 there indicated in the characters of some of the 

 species, it had not yet been so generally ascer- 

 tained, nor could it be so fully developed in 



