January 4, 19 12] 



NATURE 





et elles permettent en particulier de preciser nos con- 

 naisances sur la structure des corps cristallises." The 

 change is not without its drawbacks ; Prof. Lehmann 

 finds complacent acceptance more irritating than 

 ig-norant scepticism, and complains (p. 5), " In 

 neuestcr Zeit machen sich sogar Stimnien geltend, die 

 glauben machen wollen, es handle sich um eine liingst 

 bekannte Sache, die ganz selbstverstandlich sei." 



We discussed the scope of Prof. Lehmann 's re- 

 searches two years ago (1909, vol. Ixxix., p. 286), and 

 need not traverse the same ground again. The pre- 

 sent volume is naturally more coherent and easier tc 

 read and digest than a series of isolated papers pub- 

 lished in various journals, and it may be commended 

 to all who would fain learn of a remarkable subject. 

 In chapter x. the author gives, with illustrations. 



I'lG. 3. — Silicate-vegetation. 



d( >,criptions uf iht- various forms of the cryslallisalion- 

 microscope, the invention of which rendered his re- 

 s(-arches possible. Tho princijjal conclusions arrived 

 at may be summinl u|) briefly. The old idea of a 

 crystal as necessarily a rigid body bounded bv plane 

 faces must be definitely abandoned, as tht> author 

 says (p. 149), " Demnacii gehort auch die Bildung in 

 ebcnflachiger Form nicht unbedingt zu dem Kristall- 

 begriff." Crystals may, indeed, be solid and rigid, 

 and liquid and mobile, and there is no break in the 

 transition from one sort to the other. The ultimate 

 particles are invariably anisotropic. Isotropic crystals 

 result from the neutralisation of the action of the 

 • particles by their mutual arrangement, which is regu- 

 >lar ; amorphous substances, on the other hand, are 

 isotropic because their arrangement is irregular. Prof. 



NO. 2201, VOL. 88] 



Lehmann pomts out (p. 194), "Dass regular Kristalle 

 durch Zug und Druck doppelbrechende werden, ist 

 veilleicht teilweise darauf zuriickzufuhren, dass sie 

 amsotropen .Molekulen bestehen, welche verdreht 

 gegeneinander angeordnet sind, so dass keine Richt- 

 ung bevorzugt wird." We are left therefore with, as 

 the fundamental character of a crvstal, its power 

 under suitable conditions to grow ; it is therebv sharply 

 differentiated from an amorphous mass, which cannot 

 in any circumstances grow. It is this important 

 character which has led Prof. Lehmann to believe that 

 crystals are the agents in the growth of living organ- 

 isms. The curious and beautiful silicate-vegetation 

 affords an instance of growth of purelv unorganised 

 matter. The close similaritv in behaviour and appear- 

 ance between certain kinds of crvstals and " bacteria 

 has often been remarked, and cannot be dis- 

 missed as accidental. 



Prof. Lehmann gives us a lucid exposition of 

 the subject which has constituted his life's work 

 and has been developed almost solelv bv himself, 

 and the reasoning is rendered easier" to 'follow by 

 the aid of numerous excellent illustrations, three 

 of which we are permitted to reproduce here. .An 

 index, which might perhaps have been fuller, 

 i^ provided. The printing and the paper used 

 are both good. 



THE TIDAL SURVEY OF JAPAN. 

 T N the Journal of the College of Science of 

 Tokyo for April, 1911 (vol. xxviii., article 7), 

 Prof. Hirayama publishes results derived from 

 tidal observations made during the last sixteen 

 years at fourteen places distributed round the 

 coasts of Japan and Formosa. The tide-stations 

 were administered by the Land Survey, but the 

 reductions are in the department of the geodetic 

 committee, of which Prof. Terao is president. 



The sites of the observatories have been care- 

 fully chosen so as to give g(x:)d representations 

 of the tides in the neighbouring seas, and twelve 

 of the stations are permanent establishments, 

 while two are temporary. Samples are given of 

 the tide-curves recorded at nearly all the stations, 

 and it is clear that perturbation due to seiches 

 has been slight. Many of the observatories are 

 at somewhat inaccessible places, and therefore the 

 clocks of the gauges were regulated by the aid 

 of a simple form of sundial. The gauges them- 

 selves were for the most part of Lord Kelvin's 

 pattern, and have been found very satisfactory. 

 The paper shows that the work has been carried 

 on with Japanese thoroughness. 



In the office of the United .States Coast Sur- 

 vey a number of stencil plates pierced by holes 

 are laid successively on the tabulated hourly 

 values of the heights of the water, and 

 the numbers which are visible through 

 the holes are those which are to be added 

 together to form the sums required to furnish 

 the data for harmonic analysis. The late Dr. Borgen 

 attained the same end by means of sheets of tracing 

 paper laid on the tabulated values which indicate by 

 zigzag lines the columns for addition. Prof. Hira- 

 yama tried both those jilans, but he finally concluded 

 that the use of my tidal abacus ' was the most con- 

 venient method, and it alone was used. The work 

 involved in treating the observations at the fourteen 

 stations must have been enormously laborious, as no 

 fewer thati si\i\-si\ xcnrs of observation have been 

 reduced. 



I have not tried to make a minute examination of 



1 Proc. Roy. Soc.. vol. lii. (189a), p. 345, or " Scientific Paper*," vo!. i.' 

 p. 216. 



