138 CJironicles of Science. [Jan., 



but looking at the ensemble of these characters, he sought to estab- 

 Hsh a " natural " method of classification, following in the wake of 

 Jussieu, and doing for petrology what has already been so ably done 

 for botany. A description of his system has recently been pub- 

 lished as a posthumous work, edited by his colleague, M. Charles 

 D'Orbigny.* 



The work is divided into three parts, in the first of which we 

 learn the characters of rocks in general, the principles on which 

 their species and varieties are founded, and the method followed in 

 their classification. In connection with this section attention may 

 be called to a chapter on the determination of compact volcanic 

 rocks, which is the reproduction of an essay published as far back as 

 1815. The second part gives a systematic and detailed description 

 of all the known rocks that compose the sohd crust of the earth. 

 In this section many new species are described, and one meets for 

 the first time with such names as Harmophanite, Syenihte, Cristulite, 

 Leucostite, Mimotalcite, Cecihte, &c. The third part contains some 

 general considerations on the constitution of the earth's crust, and 

 a description and classification of the crystalhne rocks. Possibly 

 the value of the book would not have been much diminished if this 

 portion had been omitted, or at least considerably modified. As a 

 testimony, however, to the practical value of Cordier's system of 

 classification, the editor tells us that he has found by long experience 

 that firom fifteen to twenty lessons on this method are always 

 sufficient to enable a student to determine a rock at sight, even 

 when he commenced the study ignorant of the first principles of 

 Mineralogy. 



10. MINING AND METALLUEGY. 



Mining. 



The shortness of the average duration of a miner's hfe has often 

 been the subject of the most serious consideration. The Eoyal 

 Commission, of which Lord Kinnaird was the chairman, made this 

 portion of their inquiry a most searching one. It is clear, from the 

 evidence given by medical men and others, that the metalliferous 

 miner suffers in health from climbing on the perpendicular ladders 

 from great depths, from working in air deficient in oxygen, and from 

 the severe labour of boring holes for blasting in confined levels. 

 The constrained position of the man in " beating the borer," and the 

 muscular effort necessary to dehver the heavy blow, acts inju- 

 riously upon the heart and lungs. The miner has been reheved to 



* ' Description tics Rnclu-s coniposant I'ecorcc torreslrc et dcs terrains cristnl- 

 lins constituant lo sol primitif.' Ouvragc du feu F. L. A. Cordier, par Charles 

 D'Orbigny. 8vo. Turis, 18G8, pp. 553. 



