II. MINERALS, ETC. 757 



3499. Models of Crystals, made from glass plates. 



W. Ape I, Gottingcn. 



The large size of the models renders them especially useful for demon- 

 stration teaching. The angles agree with those of the natural crystals, as 

 exactly as the difficulty of manufacture will permit. The threads showing 

 the axes liave the same colour for similar axes, and a different colour for 

 dissimilar axes. In the hemihedral forms the corresponding holohedral forms 

 are included, and from the colours marked on them it can be seen whether 

 they have disappeared or remain in the hemihedral forms. The hexagonal 

 system is, according to Miller, referred to the three axes cutting each other at 

 oblique but equal angles. 



3500. Models of Crystals, in wood and wire. 



Royal Mining Academy, Freiberg, Saxony. 



3501. Tables for Instruction in Crystallography. 



Dr. F. Pfafffy Th. Biasing's Library, Erlangen. 



3503. Forms of the Isometric Systems, represented in all 

 possible combinations. P ro f- Dr. Prestel, Emdem, Hanover. 



3504. Skeleton of a Rhombohedron, with a divided side for 

 crystallographic demonstration. Albrecht, Tubingen. 



By the string placed round the dividing rods all the faces of the rhombo- 

 hedral system, of which the indices of h, k, & / are represented by three of 

 the number to 5, can be illustrated. Compare Miller's Treatise on 

 Crystallography, p. 55. 



3505. Book, " Nephrit und Jadeit nach ihren mine- 

 ralogischen Eigenschaften sowie nach ihrer urgeschichtlichen und 

 ethnographischen Bedeutung." By Heinrich Fischer, Stuttgart, 

 1875. With 131 woodcuts, and two chromolithographs. 



Prof. Leopold Heinrich Fischer, Freiburg, Baden. 



In this book is originated a new branch of mineralogy, viz., the archaeo- 

 logical and ethnographical. Hitherto the sculptures, amulets, and ornaments 

 of stone in the museums have been looked upon as show objects, but as quite 

 devoid of scientific interest. 



In this book these studies are carried out as the material of numerous 

 objects in these museums obtained both in and out of Germany, especially 

 with regard to Nephrite and Jadeite, which play such an important part 

 among the archaeological minerals, and also with regard to the rest of the 

 important minerals of this class. 



The volume also serves as a guide to the series of imitations (in wax, 

 gypsum, &c.) exhibited by Dr. Adolf Ziegler, of Freiburg, in Baden, of such 

 scientifically important and prominent original sculptures from Asia, New 

 Zealand, Marquesas Island, Otaheite, Central America, Mexico, Peru, &c. as 

 are partly exhibited in the Freiburg Mineralogical Museum and the Freiburg 

 Ethnographical Museum, and partly were lent by other museums to the 

 Freiburg Museum for the preparation of imitations. 



There can be no doubt that the presence of such imitations in the Archaeo- 

 logical and Ethnographical Museums will be a great help to this branch of 

 study, which has until now been quite neglected, but which promises to become 

 of the highest importance for the study of the most ancient races of men ; for 

 the stone remains are indestructible proof of departed periods of civilisation. 



The remains of sculpture, the archaeological records of America and 

 Oceania, so remarkable in their form and in the astonishing hardness of the 

 minerals out of which they are made, and which have hitherto been neglected in 

 Europe, will by means of these models become better known. 



