5'4 



NATURE 



[October 19, 191 1 



to the determination of the characters of minerals. 

 He rightly believes that, while a careful study ol the 

 variety of specimens contained in a large mineral 

 collection is most helpful towards acquiring facility in 

 recognising mineral species, yet it is always desirable 

 to be able to confirm a judgment by, or even to base 

 it wholly upon, a few well-chosen tests, and this book 

 is intended to assist students and others who may 

 have occasion to identify mineral specimens in carry- 

 ing out such tests. 



The opening chapter deals with the goniometrical 

 measurement and the perspective drawing of crystals, 

 the calculation of the fundamental morphological data, 

 and the measurement of refractive indices by the 

 method of minimum deviation. In the next chapter 

 the author passes on to the chemical examination by 

 means of the blow-pipe, microchemical reactions, anil 

 the quantitative determination of the precious metals, 

 coal, &c. The third chapter is concerned with crystal 

 optics, and the fourth with the special application of 

 these properties to use with the microscope. The last 

 chapter includes the remaining physical characters, 

 such as hardness, specific gravity, pyroelectricity, etch- 

 ing, melting point, and crystallisation, the phenomena 

 presented by mixed crystals being considered at some 

 length. In an appendix the author offers some hints 

 on the kind of apparatus useful for prospectors and 

 generally travellers interested in minerals, and con- 

 siders the special case of precious stones. 



The book has been carefullv written, the hints given 

 being evidently based upon the author's own experi- 

 ence, and it will be found to serve well the purpose 

 for which it is intended. 



Mikrographie des Holzes der auf Java vorkommenden 

 Baumarten, im Auftrage des Kolonial-Ministeriums, 

 unter Leitung von Prof. J. W. Moll, bearbeitet von 

 H. H. Janssonius. Dritte Lieferung. Pp. 161-540. 

 (Leiden : E. J. Brill, 191 1.) 

 This is the third part of an extensive publication, 

 designed to take advantage of a large number of 

 Javanese wood specimens collected by Koorders with 

 a view to the preparation of a forest flora for 

 Buitenzorg. The collection is unique because corre- 

 sponding herbarium material was gathered at Jte 

 same time, so that the identity of each specimen can 

 be accurately determined. The herbarium material 

 was critically examined and described in the 

 " Additamenta " noted in the title. The microscopic 

 investigation is being conducted by Mr. H. H. 

 Janssonius in great detail ; a " topographical " or 

 general description of the sections which would serve 

 for most purposes is not considered sufficient, but 

 copious details are supplied for each type of cell repre- 

 sented. Figures are only given for one species of 

 each genus, and the scale of 1 : 25 is adopted ; 

 it would have expedited reference if a figure had been 

 provided for each species on a scale of 1 : 10, enabling 

 direct comparison to be made with illustrations pro- 

 vided in several standard works. The most valuable 

 feature is the summary of anatomical characters 

 drawn up for the analytical determination of genera 

 and species. Prof. Moll suggested, in a notice of the 

 earlier parts subscribed to the Botanische Central- 

 blatt (vol. cxiii."), that it should be possible to determine 

 not only the families but genera, and occasionally 

 species, by the characters of the wood; the full con- 

 summation of this scheme is reserved for a final 

 survey. 



A book on these lines has long been a desideratum. 

 Some estimation of the magnitude of the work can 

 be formed when it is mentioned that this part com- 

 pletes a second volume of 540 pages, devoted entirelv 

 to the Disciflora? represented by 163 species or varieties. 

 NO. 2190, VOL. 87] 



When Should a Cliild Begin School? An Inquiry into 

 the Relation between the Age oj Entry and School 

 Progress. By YV. A. Winch. Pp. iii + 98. (Balti- 

 more: Warwick and York, Inc., 1911.) 

 Mr, Winch's book is an admirable example of educa- 

 tional inquiry as it should be pursued. Instead of 

 arguing on a priori grounds that children under five 

 are better at home than at school, he shows by careful 

 statistical methods what the actual effect of early 

 entrance upon school courses is. His research shows 

 in a thoroughly convincing way that those who begin 

 school about five years of age do quite as well — often 

 very much better — than those who begin at an earlier 

 age. Stated quite moderately, it is clear that it makes 

 no actual difference to the future school record 

 whether a child begins at three or at five, though 

 incidentally the figures suggest that delay beyond the 

 fifth year is actually disadvantageous — a point in 

 favour of English as opposed to German practice. Of 

 course, many school authorities have already ceased 

 to provide for children so young, not because of 

 Mr. Winch's work, but because the State has with- 

 drawn the grants. Yet it does not follow, of course, 

 that the social value of the babies' classes in the in- 

 fants' schools is nil. It is something that overworked 

 wives are relieved for a few hours a day of the strain 

 which young children in a small house commonly 

 bring. But it is abundantly clear that formal school 

 lessons of any kind before the fifth year is completed 

 are quite unnecessary. Hygienic surroundings and 

 playful occupations with abundant opportunities for 

 sleep are chiefly wanted. Trained nurses rather than 

 trained teachers, creches rather than schools, would 

 perhaps meet the situation. J. A. G. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



The Orientation of the Great Temple of Amen-Ra 

 at Karnak. 



In 1891 Sir Norman Lockyer made a magnetic survey of 

 the axis of the great Temple of Amen-Ra, at Karnak, with 

 the view of determining an astronomical date for the 

 original building. 



Since that time a great deal has been done in excavating 

 and exposing the foundations of the older work along the 

 temple axis, chiefly under the personal supervision of M. 

 Legrain, of the Department of Antiquities, who for sixteen 

 years has been the director of the explorations at Karnak. 



On my recent visit to Karnak, where I spent some 

 weeks, M. Legrain gave me the greatest assistance to 

 enable me to make a resurvey of the axis in the light of 

 the many new discoveries, and particularly in pointing out 

 the parts of the original buildings still in situ, many of 

 which he had himself uncovered, and all of which I after- 

 wards measured and centred up. 



Unfortunately, I arrived at a very unlucky time for 

 carrying out this work, as the place was crowded with 

 Arab workmen hauling out great stones from the excava- 

 tions, and gangs of boys carrying baskets of earth from 

 the diggings, all making as much noise as possible, that 

 the place was more like a busy ant-hill than the eternal 

 calm which might be expected in an Egyptian temple. In 

 addition to this, the tourist season was at its height, and 

 personally conducted parties were continually passing up 

 and down, and naturally made a highway of the axis where 

 I had set up my instruments. One soon forgets small in- 

 conveniences ; but tbe torment of the insects, when both 

 hands were occupied, is brought to mind by a remark 

 made to me by a passing gentleman from the fat West 

 when he said, " Mr. Surveyor, I guess you're having a 

 bully time with them flies." 



