Dec. 4. 1873] 



NA TURE 



tion of minerals deals with their chemical peculiarities. 

 It occupies not quite four pages, and has evidently been 

 inserted for the sake of completeness, that the learner, 

 even thou.t,'h specially intent upon microscopic work, should 

 not be left wholly in the dark as to what he can accom- 

 plish himself in the way of chemical analysis. 



The second and by much the more important and 

 useful part of the treatise deals with the microscopic 

 characters of minerals, and more particularly of those 

 which enter largely into the composition of crystalline 

 rocks. Considerably over a hundred minerals are treated 

 in this way, and these, of course, include all those which 

 are of prime consequence to the petrographer. For 

 example, the felspars, augite, hornblende, calcite, quartz, 

 pyrite, and other common ingredients of rocks are fully 

 described. The author has worked hard at the subject 

 himself, though he has not hitherto published much. One 

 excellent feature of his volume is the full references which 

 he gives to the papers of previous writers on the same sub- 

 ject. Not only at the beginning of the description of each 

 mineral docs he quote, in legible print, the titles of the 

 papers in which information about the microscopic cha- 

 racters of that mineral may be found, but at the end 

 of the volume he inserts a long alphabetical list' of 

 authors, with the names and dates of their papers. This 

 is a most welcome boon to all those who, especially in our 

 own country, have the courage to attack the voluminous, 

 but hitherto hardly known or accessible literature of the 

 subject. Two sorts of illustrations are given — woodcuts 

 and coloured plates. Of the former rather more than 

 100 occur, mostly illustrative of the crystalline forms or 

 optical characters of the minerals. They do not call for 

 special remark, except that they might with advantage 

 have been more numerously inserted to explain the in- 

 ternal peculiarities of some of the numerous species 

 described. The coloured plates are singularly effective. 

 Ten in number, they contain sixty figures of the micro- 

 scopic structure of upwards of thirty more or less com- 

 iTion minerals. We have seen nothing so good since 

 Vojelsang's large and admirable drawings published six 

 years ago at Bonn. It appears that it was origi- 

 nally intended to have included more plates, but that 

 llie cost proved so great that the number had to be 

 restricted to ten. This, no doubt, is the reason why some 

 not very important minerals have a place on the ])lates, 

 while others of greater consequence have been left out. 



Thii volume, even had it been less painstaking than it 

 is, would have deserved commendation as an introduction 

 to a study for which no text-book at all previously existed. 

 I5ut, as its author frankly acknowledges, it will not and is 

 not intended to supply the place of actual personal work — 

 " he vvho would learn microscopic mineralogy must to the 

 cutting-lathe and the microscope." The greater the number 

 of observers who can be induced to betake themselves to 

 tliis pursuit, the sooner may we hope for some definite 

 and broad well-established results. -Vt present the work 

 accomplished, most excellent and praiseworthy though it 

 be, belongs rather to the hewing-of-v.ood and drawing-of- 

 water order. The facts are weekly accumulating out of 

 which, in the end, a flood of light will unquestionably be 

 cast upon the genesis of rocks, and consequently upon 

 the history of the earth itself. All honour, therefore, to 

 the enthusiastic workmen by whom this labour is so 



cheerfully and actively undertaken, and none the less to 

 Mr. Rosenbusch for publishing a most useful volume, 

 which will, no doubt, increase their numbers. 



OUR BOOK SHELF 



Solid Geometry and Conic Sections, "with Appendices on 

 Transversals, and Harmonic Division, for tlie Use of 

 Schools. By J. M. Wilson, M.A. Second Edition. 

 (Macmillan and Co., 1S73.) 

 Elementary Geometry, Books i. ii. ill., following the 

 " Syllabus of Geometry," prepared by the Geometrical 

 Association. By J. M. Wilson, M.A. Third Edition. 

 (Same publishers, 1873.) 

 The portions of the title-pages we have above given suffi- 

 ciently indicate the scope of the two works under review 

 and the measure of acceptance they have met with. 

 As we have already given an account of 'the former 

 work it will not be necessary to give any detailed 

 account of it now. It has been considerably im- 

 proved by the addition of some eighteen pages of new 

 matter, consisting of a slight rearrangement of Section 1., 

 which treats of planes, the addition of a section (IV.) on 

 the sphere, which is almost entirely new to the work, and 

 some slight changes in the articles on the Ellipse and 

 Hyperbola. The result is a close approximation to the 

 views we expressed in our previous notice, and the book 

 can be recommended as an excellent, if not the only 

 English, treatise suited to the requirements of candidates 

 for the first B.A. Pass Examination of the London Uni 

 vcrsity. We point out an obvious slip of inscribed for 

 eirCHinscribcd cXtcXts, on p. 55 ; in the filth paragraph, p. 

 56, all the A's but one should be accented; the last e.\er- 

 cise, on p. 68, is misplaced, and repeated in its proper 

 place, as Exercise 29 on p. 71 ; other minor slips can be 

 easily corrected. 



The " Elementary Geometry" is to our mind a vast im- 

 provement upon the first edition ; the changes are all, we 

 believe, in the right direction. We never took kindly 

 to that first edition ; the most confirmed euclidophilist 

 must be led by a perusal of this to a more favourable view 

 of the aims of anti-euclidean agitators. Seeing that the 

 aim of teachers of both parties, if they are in earnest, 

 should be the improvoneiit of geometrical teaching, we 

 trust that neither party will lose sight of this high mark 

 through intervening clouds of dust raised on irrelevant 

 grounds. 



The " get-up " of both books is excellent, the printing 

 of the " Elementary Geometry " most accurate (we have 

 detected but one or two slight errors). We wish to add a 

 closing remark on this subject of errata : we consider that 

 an author is bound to bestow every care in this matter, 

 and it is with regret that we find some works of recent 

 data have been brought out, it is reasonable to suppose, 

 in such haste to meet a possible demand for thtm that 

 they may be said to teem with mistakes. This entails 

 great waste of time and trial of patience upon junior 

 students and appears to us unfair treatment. R. T. 



LETTERS TO THE EDITOR 

 [ 7lu- Editor does not Iwld himself responsible for opinions expressed 

 by his correspondents. No notiee is taken of anonymous 

 communications.'] 



The Southern Uplands of Scotland 

 To the able .irticles on this subiect contributed to your pages 

 by Prof, llarkntss, I should like to be perniitied to make an 

 addition. He has referred to some opinions and observations of 

 mine, but I am anxious that it should be generally known to 

 what an extent the results olitaincd by the Geological Survey 



