396 Miscellanies. 
have often been disposed to question the propriety of denominating 
the study of minerals, a science; and we are acquainted with Bota- 
nists who have actually abandoned it on the ground that its species 
were indefinite, and that no scientific characters existed for their 
recognition. 
We give the following as an outline of Mr. Shepard’s work. 
He treats the science in five parts, under the following general 
heads; viz. Terminology, Classification, Nomenclature, Character- 
istic and Physiography. 
Part I. or Terminology, embraces an explanation of the natural 
properties of minerals, or those which they exhibit while in their 
natural state. ‘These are considered under three divisions; viz. 
1, such as refer to simple minerals; 2, such as refer to compound 
minerals; 3, such as are common to both. ‘The first of these divis- 
ions, to which a section of seventy one pages is devoted, embraces 
the geometrical properties of minerals, or such as refer to space,— 
the relations of structure, of surface, and the phenomena of double 
refraction. In treating of the geometrical properties, or what is 
more usually understood as constituting the science of crystallo- 
graphy, the following order is pursued. 'To adapt the work to per- 
sons ignorant of solid geometry, a few pages are devoted to element-_ 
ary definitions in that branch. ‘The following propositions are then 
laid down and illustrated; viz. ‘1. Certain mineral species affect: 
peculiar forms,”—2. “ Several different forms are frequently found 
in different individuals of the same species,”—3. “ The different crys- 
talline forms belonging to each species may be conceived to be derwed 
by certain laws from one type or fundamental form.” The number 
of such primary forms in the mineral kingdom is then announced ; 
and each of them is described and illustfated in its principal geo- 
metrical properties. ‘To this succeeds the consideration of those 
symmetrical modifications which these forms undergo from the re- 
placements of their edges and angles, and the new figures which 
"are produced when the replacements extend so far as to extinguish 
the faces of the primary form. 
The imperfections of crystals in respect to their forms is next 
treated of, and the methods employed for ascertaining the angles of 
crystals. Then follows an account of the internal structure of erys- 
tals, or the laws of cleavage. Here the author has deviated from 
the practice of most writers on elementary mineralogy, in having 
passed over in silence the subject of the origin of crystals through 
