.3^. SOME NEW BOOKS. 471 



suggestive of a New Year's entertainment, but not at the Royal 

 Institution. Chapter V. contains some valuable applications of 

 physiology to practical life ; it is reassuring to those of us who are 

 compelled to lead a more or less sedentary existence to learn that 

 the best form of exercise is walking. But if we are to select that 

 form of exercise which is most in accord with our physical organisa- 

 tion, we ought not to forget that the arms should be used as well as 

 the legs; Dr. McKendrick omits to mention that according to "them 

 perfane Darwinists " climbing would probably be an excellent 

 pursuit ; the safest and best imitation of this is afforded by the 

 Gymnasium. 



The Microscopic Determination of Rock-forming Minerals. Tabletzui dlya 

 Mikroskopicheskagho opredyeleniya porodoobpazuyushchikh Mineralov. By 

 F. Loewinson-Lessing. 4to. Pp. xii. and i6, and folding tables. St. 

 Petersburg, 1891. 



As an indication of the great strides now being made in Russian 

 geology, we are glad to be able to call attention to this admirably- 

 compiled set of tables of the rock-forming minerals, which, but for 

 the fact that they are written in Russian, would probably prove of 

 greater service to general students than either of those previously 

 issued. Dr. Loewinson-Lessing points out in his preface that he has 

 been impelled to write this work by the fact that so many Russian 

 students are unable freely to use those in French and G^-rman. He 

 has, however, arranged the work on a plan that seems a great 

 advance on those previously attempted. The tables of Rosenbusch 

 Michel-Levy, and Lacroix, and the earlier ones of Doelter and 

 Hussak, give the name of a mineral first, and after that its characters ; 

 thus, if we know the mineral, these give us an admirable method of 

 verifying the determination. But if a student is quite at sea as to 

 the name of some mineral new to him, these tables give him but 

 little assistance. In Dr. Loewinson-Lessing's tables, however, the 

 method is reversed ; if you know the characters of the mineral you 

 can determine its name. In addition to a large synoptical table, he 

 gives five tables, each using one set of characters. The first table 

 is based on examination in polarised light ; the minerals are grouped 

 as opaque, semi-transparent, and transparent ; the last is divided 

 into colourless and coloured, and, by aid of the nature of the extinc- 

 tions, the pleochroism, notes on the general aspect, &c., the species 

 may readily be traced. The remaining tables are devoted to the 

 external morphological characters, the discrimination of the crystalline 

 systems and their application, and the more technical optical charac- 

 ters. As these tables are intended mainly for students and general 

 v/orking geologists, only those minerals are included which are of 

 practical importance. A little over 80 are included, and the long 

 lists of little-known minerals that fill up the tables of Rosenbusch 

 and Michel-Levy, are wisely excluded. Dr. Loewinson-Lessing's 

 experience, both as a teacher and a skilled petrologist, is sufficient 

 guarantee of the wisdom of his plan and the accuracy of its execution. 



English Botany. Supplement to the Third Edition. Part II. (Orders xxiii. to 

 xxvi.). Compiled and illustrated byN. E. Brown. 4to. Pp. 59-160, with one 

 coloured plate. London : G. Bell & Sons. 



In Natural Science for June we noticed Part I. of the Supplement 

 to the Third Edition of English Botany. Part II. is now to hand, 



