144 Analyses of Books. [Aug. 



almost indispensably necessary, — chemists, writers on mineral- 

 ogy, and ey en professors of that science (we speak not at random, 

 or from doubtful authority), appear to have altogether neglected 

 crystallography, properly so called. There is a variety of cir- 

 cumstances which tend to allay the surprise that might other- 

 wise be excited by these facts, though they cannot diminish our 

 regret that so beautiful, and at the same time so important a 

 branch of study, should have been thus treated. Among these, 

 the in some measure abstruse mathematical aspect in which 

 crystallography was presented by Haiiy, contrasted with the 

 easy empirical determination and nomenclature of crystals 

 taught in the Wernerian school, which is probably the most 

 defective part of the system followed by its professors ; and the 

 apparently confined applicability of this science to practical pur- 

 poses in the arts of life, appear to have had great enect in limiting 

 Its cultivation. It must be admitted likewise, that certain incon- 

 venient and even unphilosophical views embraced by the method 

 of Haiiy, have also contributed to this effect. 



Such then being the case, we cannot but congratulate the 

 scientific pubhc on the appearance of Mr. Brooke's " Familiar 

 Introduction to Crystallography," a work, we conceive, which is 

 calculated to be of much utility in remedying the evil to which 

 we have just adverted. We proceed to a brief review of its 

 contents. 



It commences with a series of definitions, some of which 

 are of a very elementary nature, so as to accommodate those 

 who are even unacquainted with the first rudiments of geo- 

 metry. These are succeeded by a particular and explanatory 

 account of the principle and method of using both the common 

 and the reflective goniometer. To this follows Sect. I, contain- 

 ing a brief general and historical view of the science of crystal- 

 lography. In Sect. II, Mr. Brooke first describes the Abbe 

 Haiiy's system of molecules, and then details, nearly in the 

 following terms, a new theory on this subject. We must omit 

 the diagrams with which this theory is illustrated, but it is so 

 clearly detailed, that the reader may, we think, acquire a correct 

 knowledge of it without them. 



" The very complicated system of molecules which the Abbe 

 Haiiy has, by this view of the structure of the octahedron and 

 dodecahedron, introduced into his otherwise beautiful theory of 

 crystals, and the apparent improbability that the molecules of the 

 cube, the regular octahedron, tetrahedron, and dodecahedron, 

 among wJiose primari/ and secondarj/ forms so pe? feet an identity 

 subsists, should really differ from each other, have induced iue to 

 propose a new theory of molecules in reference to all the classes 

 of octahedrons, to tne tetrahedrons, and the rhombic dodecahe- 

 drons, which I shall now state. 



" Fluate of' lime, as we have seen, has for its primary form a 

 regular octahedron, under which it sometimes occurs in nature ; 



