April 8, 1922] 



NA rURE 



441 



annot be compared in full detail with that of neighbour- 

 ing countries. 



There are one or two slips ; for example, " right 

 hand rear section " on page 179 should be " right hand 

 front section." The diagram in Fig. 2 is not sufficiently 

 explained to be intelligible to those readers who are not 

 already familiar with the theories of Prof. Bjerknes. 

 The glossary at the end is not very full : we look 

 in vain, for example, for orographical rain and for con- 

 \ection. The book fills a gap in meteorological litera- 

 ture, and the concluding chapter on the economic 

 application of rainfall data is an indication of how 

 widely it should be studied, not only by meteorologists, 

 hut also by those outside their ranks. 



(2) " Etudes elementaires de Meteorologie pratique " 

 scribes the ideal arrangement of stations for a 



meteorological service, the instruments used, including 

 captive balloons, pilot balloons, and aeroplanes, and 

 the general procedure of such stations. Part 2 is. 

 devoted to problems of pressure and wind, and part 

 3 discusses forecasting. Squalls and thunderstorms 

 come in for full treatment, and also the sudden clearings 

 of the sky, " eclaircies " ; the author's experience as 

 chief of the meteorological service of the Armies of the 

 Centre probably led him to study this phenomenon, 

 so important for aviation and hitherto much neglected.' 

 The author advocates numerous observation posts, 

 so that a line squall, for instance, may not pass un- 

 noticed between the regular stations of the service. If 

 such a system had been adopted in this country during 

 the war much serious damage might have been avoided 

 at aerodromes in the South of England. The work 

 does not pretend to be a meteorological handbook, but 

 it is valuable for those engaged in official meteorological 

 work, and it discusses interesting points, some of which 

 may still be rather controversial. The chief fault of the 

 work, if fault it be, is that it is unnecessarily full, which 

 would have made an index all the more useful. 



(3) Mr. Stenhouse's httle book is intended for school 

 students and for the general reader. The subject, 

 including something of dynamic meteorology, is shortly 

 and clearly explained. But there are a number of in- 

 accuracies which ought to be corrected if the work runs 

 into further editions. The coldest time of day is not a 

 little after midnight but a little before sunrise ; strato- 

 cumulus is scarcely a combination of stratus and 

 cumulus, nor is cumulus the typical cloud of the middle 

 layer. Alto-cumulus is not even mentioned ; and the 

 distinction between cloud sheets and clouds of convec- 

 tion is not brought out. There are some good photo- 

 graphs, but they have not been well selected ; snow 

 and frost scenes do not teach anything in particular, 

 and a more typical selection of cloud forms should have 

 been given ; the clouds in Plate VI., though given as 



cumulus, are nothing of the kind ; the top picture in 

 Plate VII. has been inverted. The diagrams of sections 

 across weather maps make a misleading use of the term 

 pressure-gradient. In spite of faults, however, the 

 book forms an attractive introduction to meteorology 

 for beginners. 



(4) Unfortunately this cannot be said for Mr. 

 Redway's " Handbook of Meteorology," which contains 

 many inaccurate statements. Hydrogen, on account of 

 its lightness, is stated to be thrown off into space by 

 the rapid movement of the earth ; air currents " are 

 deflected by the rotation of the earth on its axis easterly 

 in tropical latitudes, and westward beyond the tropics "; 

 the isothermal layer separates the stratosphere and the 

 troposphere ; the stratosphere is stated to be radio- 

 active, indicating the presence of electrified dust 

 particles, and the reason why cloud particles remain 

 suspended is stated to be unknown, and electrification 

 is suggested as a possible explanation ; these are only 

 a few of the surprising statements to be found in this 

 work. C. J. P. Cave. 



Freshwater Ciliate Infusoria and Heliozoa. 



(i) Etudes sur les Injusoires d'Eau douce. By Dr. E. 



Penard. Pp. 331. (Geneve : Georg et Cie, 1922.) 

 (2) The British Freshwater Rhizopoda and Heliozoa. 



By J. Cash and G. H. Wailes. Assisted by J. 



Hopkinson. Vol. 5. Heliozoa. By G. H. Wailes. 



Pp. vi + 72 + ii plates. (London: for the Ray 



Society, 1921.) 



(I) 



T 



HERE is probably no large sheet of fresh 

 water that has been so thoroughly investi- 

 gated, so far as its fauna of protozoa is concerned, as 

 the Lake of Geneva. Forel, Jean Roux, Penard, and 

 others have shown its richness in variety of form, in the 

 number of species, in cases of parasitism, and in adap- 

 tations to other special habits of life. They have set 

 an example which we might well follow in regard to our 

 English lakes, about which we still know so little. 



Dr. Penard has already published massive volumes 

 on the Rhizopoda, the Heliozoa, and the Acinetaria of 

 the lake and neighbouring waters, and the present 

 volume on the ciliate Infusoria, not restricted in this 

 case to protozoa of the immediate locality, is no less 

 imposing than the others. 



Dr. Penard's work will doubtless me^ with a great 

 deal of severe criticism, because his histological methods 

 are primitive and inefficient, his illustrations badly 

 drawn and abominably reproduced, and the arrange- 

 ment of the text is most inconvenient for the reader. 

 But he disarms criticism, to some extent, as regards the 

 first defect by his frank admission that all his observa- 



NO. 



2736, VOL. 109] 



