June 19, 1914] 



SCIENCE 



911 



The plan includes a (somewliat obsolete) 

 system of classification, a chapter on geological 

 history, one on distribution (such as can be 

 obtained from existing manuals), on reproduc- 

 tion (omitting reproductive acts), on food, 

 evolution, instinct, intelligence and uses, with 

 an. index. 



Taken for what it is, a compilation from 

 the literature for popular use, it should not 

 be too harshly criticized, and in fact presents 

 a useful compendium of widely scattered data, 

 not elsewhere brought together. 



It is well illustrated, chiefly by reproduction 

 of the plates of the well-known " Manual of 

 the Mollusca," by S. P. Woodward, first pub- 

 lished in 1850, and in its time easily the best 

 of the smaller manuals of the mollusca. 



Taking into consideration the purpose of the 

 book, the chief criticism which in justice 

 to the reader we feel should not be suppressed, 

 touches on the too ready acceptance by the 

 author of some statements by others which 

 stand in desperate need of confirmation. 



For instance the assertion that the murices 

 utilize the spur or projecting spine of the 

 aperture of the shell to pry open bivalves 

 which they intend to devour, is almost pre- 

 cisely on a level with the statement that a man 

 can sit in his own lap, and would be possible 

 only in space of the fourth dimension. In the 

 most charitable view the author of this asser- 

 tion united to a lively imagination very im- 

 perfect observation. Such notions touch the 

 imagination of the ignorant, but have no 

 proper place in scientific literature. 



Also the assertion that the shell-bearing 

 Pteropoda are derived (p. 56) from the Bulla- 

 like Tectibranchs (originating with an anat- 

 omist of limited experience with mollusks) is 

 hardly compatible with the ascertained facts 

 that shell-bearing Pteropods occur in the Cam- 

 brian; while the Bulloid Tectibranchs first 

 appear near the close of the Carboniferous 

 (p. 4Y). 



Here and there such questionable statements 

 mar the generally high average of accuracy 

 of this little compendium, but, on the whole, 

 it will fulfil a useful purpose. 



Wm. H. Dall 



PRINCIPIA ATMOSPHERICA 



1. Upper Air Calculus and the British Sound- 



ings during the International Week (May 

 5-10), 1913. By W. N. Shaw. Journal 

 of the Scottish Meteor. Soc, Vol. XVI., 

 No. XXX., p. 167. 



2. Principia Atmospherica. A Study of the 



Circulation of the Atmosphere. Proc. 

 Boy. Soc. Edinhurgh. Eead December 

 1, 1913. 



3. Principia Atmospherica. An address be- 



fore the Mathematical Society, January 

 7, 1914. Privately printed. 



4. The Interpretation of the Results of Sound- 



ings with Pilot Balloons. Quar. Jour. 

 Roy. Meteor. Soc, April, 1914. 



In these four recently issued pamphlets, 

 Dr. W. N. Shaw, the progressive director of 

 the British Meteorological Office throws wide 

 open a new door in aerology through which we 

 seem to catch sight of that great desideratum, 

 the forecast based on definite laws, or per- 

 haps it would be the part of wisdom to say, 

 definite foreknowledge of the structure and 

 energy distribution in " highs " and " lows " 

 in connection with the flow of air at different 

 levels. 



It is only a short time since W. H. Dines, 

 studying numerous upper air observations, 

 came to the conclusion that the differences of 

 pressure at the earth's surface were of the 

 same order of magnitude as those at a height 

 of nine kilometers and therefore the distribu- 

 tion must be regarded as controlled by condi- 

 tions at the base of the stratosphere. In study- 

 ing this remarkable result, Shaw examined the 

 physical conditions necessary for the building 

 up of pressure between points at the same 

 level in two verticals and found that the differ- 

 ence in the influence of the stratosphere and 

 troposphere is attributable to the character- 

 istic difference of temperature. He establishes 

 a formula for the increase of pressure differ- 

 ence per meter of height and a second equa- 

 tion which gives the gi-adient wind velocity 

 at any level. This latter is used to explain 

 the variation of wind velocity with height 

 and in particular the falling-off in velocity in 



