Reviews — L. Fletcher's Guide to the Mineral Gallery. 33 



judiciously we tliink, adopted the historical method. The difficulties 

 which confront the individual in his study of minerals are precisely 

 those which have been encountered and surmounted by successive 

 generations of mineralogists in the past. In the space at his com- 

 mand, the author can of course do little more than sketch in brief 

 outline the evolution of our knowledge concerning the crystallo- 

 graphic forms, the chemical composition and the physical properties 

 of minerals, but so admirably is this done that we cannot refrain 

 from expressing a wish that the excellent method of the author 

 should be fully developed. A handbook of mineralogy, constructed 

 on the same lines, would be of immense service to the student, and 

 w^ould go far towards redeeming mineralogy from the reproach it 

 undoubtedly suffers under at present, of being one of the dullest 

 of sciences. 



Students have, however, abundant cause for gratitude to the 

 Keeper of the Mineral Collections for what he has already done for 

 them, by the selection from the rich stores of the Museum of admirable 

 series of specimens illustrating the chief characters of Minerals. 

 The different systems of crystallization, the variations in the develop- 

 ment of crystal faces, the formation of twins, and crystalline 

 aggregates, together with illusti-ations of dimorphism, trimorphism, 

 isomorphism and pseudomorphism, are all exemplified in this way. 

 Similarly, the physical properties of minerals are illustrated by 

 series showing the scales of colour, lustre, and other optical character- 

 istics ; of cleavage, fractui'e, structure, and of those other properties 

 which can only be determined by experiment. More advanced 

 students will find in the very large collection of wood models of 

 crystals, of natural and artificial crystals, and of different varieties of 

 pseudomorphs, abundant materials demanding their attention. 



The systematic collection remains in much the same condition as 

 it was at Bloomsbury, except in so far that the increased space has 

 permitted of diminished crowding of specimens, and of the intro- 

 duction of fresh varieties. No classification of minerals is likely to 

 command universal assent, and that employed at the Museum may 

 fairly claim to present as many advantages and as few disadvantages 

 as any of its rivals. 



Persons in the constant habit of consulting the Collection will 

 find that, by a very thoughtful arrangement, recent additions by 

 purchase or donation are exhibited in a special case for a short time 

 previous to their dispersion through the Collection. 



We are glad to find from this guide that the Keeper of the 

 Collection is alive to the fact that Mineralogy forms the Alphabet 

 of Petrography. Time has not yet permitted of the arrangement of 

 the Rock-Collections of the Museum ; and, until this is done, the 

 Mineral Gallery remains incomplete in one of its most important 

 departments. The general public, as well as students, will find 

 much of interest in the Pavilion, where, in addition to the meteorites, 

 are gathered together many remarkably large examples of special 

 minerals and rocks, with illustrations of their economic value. 



J. W. J. 



DECADE III. VOL. II. — NO. I. 3 



