520 Reviews — Professor J. W. Gregory — What is a Mineral ? 



head rather than director. An assistant once appointed was left 

 practically to his own devices ; but there was something about the 

 personality of the director that impelled each one to do faithful work, 

 that made the unambitious man ambitious." Lesley did all he could 

 to encourage his men to work well and accurately, and spared no 

 pains to make the published maps and reports worthy of the State. 

 It was observed by one of his assistants, Dr. H. M. Chance, that 

 "probably no public organization was ever less bound by the red- 

 tape of officialism". 



More than 120 volumes of Survey Reports passed through Lesley's 

 hands, and eventually he undertook a "Final Summary Report", 

 publishing two volumes and preparing a portion of the third and last 

 volume, embracing in all more than 1800 octavo pages; but failing 

 strength forbade the completion of the concluding chapters, the 

 writing of which was delegated to others. 



In an autobiographical letter written by Lesley to a friend in 

 February, 1882, he modestly remarks — "The only original ideas in 

 geology for which I could venture to claim credit are, (1) the deter- 

 minations of the present system of surface drainage by the dimpled 

 form of the plicated original surface ; and (2) the production of all 

 modern topography chiefly by the underground dissolution of limestone 

 strata, of all ages." These remarks, which we presume were based 

 on his Pennsylvanian work, will be of interest to those who in recent 

 years have given attention to the subject. 



The very ample record which Mrs. Ames has given in these two 

 volumes is sufficiently varied to attract many readers interested in art, 

 theology, and politics, as well as science. There are memoranda 

 relating to the Civil War and other momentous matters ; but the 

 chief interest is the biographical study of two high-minded individuals. 

 While it is pleasant to read of Lesley's " intense interest in his pro- 

 fession, his real love of and satisfaction in hard work, his delight in 

 nature", it is pleasant also to read of his charming helpmate, and of 

 the closing tranquil years which they spent together in their country 

 home at Milton. 



H.B.W. 



II. — What is a Minekal ? 



rnmS question forms the title of an interesting essay by Professor 

 J. J. W. Gregory (Trans. Inst. Mining Eng., read February 10, 

 1909). The subject is one that has for many years proved attractive 

 to lawyers and scientific witnesses ; it was referred to in the Geological 

 Magazine for December last (p. 564) under the heading " Is China 

 Clay a Mineral?" and it is of special concern in connexion with 

 the present Parliamentary Budget and the question of " ungotten 

 minerals ". 



Professor Gregory has entered very fully into the definitions given 

 by various authorities, and shows that all the explanations of what 

 is meant by a mineral fail from a scientific point of view, whether we 

 speak of simple minerals or mineral species as distinguished from 

 rocks. Thus physical properties, chemical composition, and crystalline 



