624 



SCIENCE. 



[N. S. Vol. V. No. 120. 



tion of the boreal mollusca. For this reason 

 the till of the lower St. Lawrence valley seems 

 to have been deposited under marine condi- 

 tions, covering up all the marks made by the 

 earlier ice sheets. Hence it is not strange that 

 the Canadian geologists have so generally given 

 the largest place to icebergs in their conceptions 

 of the work done in the ice age. 



The perusal of this volume clearly shows the 

 great efficiency of the Director and his assist- 

 ants in carrying on the work so ably com- 

 menced by Logan and Selwyn. The field work 

 has been carried on economically and success- 

 fully. While theories of divers kinds are ad- 

 vocated, there seems to be no attempt to distort 

 the facts to square with preconceived notions, 

 and all will hope that abundant means will be 

 continuously supplied to the survey organiza- 

 tion to carry on its explorations in a manner 

 honorable to the Dominion government. 



C. H. Hitchcock. 



Tables for the Determination of Minerals hy Phys- 

 ical Properties ascertainable with the aid of a few 

 field Instruments based on the system of Prof. 

 Br. Albin Weisbach. By Peesifoe Feazee. 

 Lippincott. 1897. 4th edition enlarged, 

 163 pp. 



The first edition of this book appeared in 

 1874 and has been followed by the succeeding 

 editions at varying intervals (1877, 1891, 1896). 

 This is really an authorized translation of the 

 German work of Weisbach, to which Professor 

 Frazer added the empirical formulae best repre- 

 senting the data at hand. Few changes were 

 made till the publication of the third edition 

 which appeared rewritten and considerably 

 changed in detail, though following the lines 

 laid down in the first edition. The chemical 

 formulae previously used were replaced by those 

 given by Groth in his ' Tabellarische Uebersicht 

 der Mineralien,' and to the tables were added 

 the characteristic habit, structure, fracture, 

 specific gravity and association of the minerals. 

 The present edition is an enlarged and cor- 

 rected reprint of the preceding. To the seven 

 hundred and sixty odd species and subspecies 

 previously included, there have been added a 

 hundred and thirty-five others, which embrace 

 several old and well known species, like micro- 



cline, and many minerals which recently have 

 been described or rendered of economic im- 

 portance, like monazite. 



As in the earlier editions, the only instruments 

 necessary are a knife, streak table, file and 

 pocket lens. The classification is based on the 

 lustre, streak and hardness, thus dividing the 

 minerals into sixteen different classes upon 

 criteria which are easily determined by the 

 practical manipulator. The book is intended 

 to be of service to the student, as an artificial 

 aid to memory ; to the field geologist, as a re- 

 minder and handy book of reference for proper- 

 ties of unusual minerals ; and to the amateur, 

 as an incentive to more accurate observations. 



The author, for the sake of economy, in 

 using the old electrotype plates, has, in a meas- 

 ure, decreased the value of the book, as their 

 use has caused the retention of features which 

 to-day savor of an earlier period in mineralogy. 

 At the present time there is a tendency to dis- 

 card even the well known crystallographic 

 symbols of Naumann in favor of the Miller sys- 

 tem. The present book, however, retains the 

 abbreviated Naumann symbols suggested by the 

 elder Dana, without incorporating the modifica- 

 tions introduced in the last edition of E. S. 

 Dana's Manual of Mineralogy. A still more 

 pronounced archaism is the introduction of 

 such ' mineral species ' as pitchstone and perlite 

 which belong to rocks and not to minerals. 

 Similar criticism might be passed on the am- 

 biguous use of the term ' andesite, ' which on 

 page 92 is used to designate a mineral, while on 

 page 99 it designates a rock ; or the term pegma- 

 tite, which is given as a varietal name for ortho- 

 clase. 



Turning to the tables themselves, there seems 

 to be looseness in the choice of values given for 

 hardness and specific gravity ; the habitat or 

 association of the minerals, and the symbols 

 used as abbreviations. 



In turning over the pages, the eye catches 

 such deviations from the hardness, as on page 

 90, where the opal is ranked as ' 5 ' (Dana 

 5.5.-6.5), or the separation of 'andesite' on 

 page 92 from laboradorite on page 100 (both 5- 

 6). The choice of values for density may be 

 illustrated by those given in the mica group, 

 where the higher limits seem to be preferred, 



