56 Canadian Record of Science. 



sive that from a single volume in the first edition the work has 

 grown to three ponderous volumes of which the first, just published 

 comprises no less than 845 pages. The work has been entirely 

 rewritten, as it was found that owing to the great strides which 

 have been made in petrographical science little or nothing in the 

 original edition could now be reproduced. 



The work has been eagerly expected for some years past but 

 various causes have contributed to delay its appearance, among 

 others the fact that the author's time has been largely devoted to 

 editing successive editions of Nauman's Mineralogy, so extensively 

 used as a text-book in Germany. The second and third volumes 

 however are also finished and are promised within the present 

 year, thus completing the work. 



The work aims at being a complete compendium of the whole 

 science of petrography, incorporating the results of all the liter- 

 ature of the science up to date, with a critical treatment of certain 

 subjects. It is thus essentially one of those monumental 

 summaries of a science, which are so useful to investigators and 

 to advanced students, and which are given to the world principally 

 by the German Universities. 



The present volume deals first with general Petrography, under 

 thirteen headings, as follows : General Characters of Rocks ; 

 Methods of Petrographical Investigation ; Form and Structure 

 of Rock Constituents; Mineralogical Composition of Rocks; Struct- 

 ure of Rocks ; Secretions, Concretions, Inclusions, etc. ; Joints, etc.; 

 Mode of Occurrence of Rocks ; Transitional Forms ; Magnetic and 

 Thermal Relations ; Origin of Rocks ; Alteration of Rocks ; Classi- 

 fication of Rocks. 



This is followed by a description of the general characters of the 

 Massive Igneous rocks which closes the present volume- 



It will thus be observed that the work is not confined to Petro- 

 graphy in the narrower sense in which the word is usually 

 employed but treats in a general way of the arrangement of the 

 various rocks in the architecture of the earth's crust, a depart- 

 ment of science usually known as Structural Geology, as well. 

 No cuts or illustrations are given, and although these are not 

 especially required in the treatment of that portion of the subject 

 dealt with in the first volume, it is feared that their absence in 

 the subsequent portions of the work, dealing with microscopic 

 petrography, will make itself felt. It is often a matter of regret to 

 the reader that Prof. Zirkel, when presenting the results of the 

 work of others and their opinions on debated points, has not more 

 frequently given his own opinions, which in many of these cases at 

 least would carry great weight, but in such an exhaustive treatise 



