912 



SCIENCE 



[N. S. Vol. XXXIX. No. 1016 



the stratospliere. In the second paper Sliaw 

 carries the application of the equations some- 

 what further and making certain assumptions 

 works out temperature and pressure from wind 

 velocity at successive heights. There is also 

 a statement of certain axioms or laws of 

 motion and applications of the laws in prac- 

 tical meteorology. The laws stated briefly are 

 (1) relation of motion to pressure; (2) com- 

 putation of pressure and application of gaseous 

 laws ; (3) convection, which is expressed as the 

 descent of colder air in contiguity with air 

 relatively warmer; (4) the limit of convec- 

 tion, defined as that portion of the atmosphere 

 where there exists a sensible fall of tempera- 

 ture with height, and (5) the law of saturation. 

 The irregular variations in temperature- 

 difference as given by a pair of soundings with 

 registering balloons; and the curious local 

 irregularities of wind disclosed by pilot bal- 

 loon ascents, hitherto explained as uncer- 

 tainties of observation, are now in Dr. Shaw's 

 opinion seen to be important as indicating 

 complex structure of the atmosphere. If 

 Shaw's reasoning is correct then it may be pos- 

 sible to get from one pilot balloon as m.uch 

 information for practical purposes as from 

 three registering balloons. The distribution 

 of isobars at 4 kilometers as computed by 

 Teisserenc deBort is also considered and the 

 law of convection applied. One sentence is 

 significant and may be quoted. " All the main 

 air-currents of the globe have pressure-distri- 

 butions to guide them. They can not usefully 

 be called convection currents." There is also 

 a most suggestive reference to the flow of air 

 down the Arctic and Antarctic slopes. It ap- 

 pears likely that whenever in a mass of air, 

 temperature-fall is in the opposite direction to 

 pressure-fall, great change in the horizontal 

 distribution of pressure underneath is the re- 

 sult; and many of our local variations of pres- 

 sure may fairly be attributed to the reactions 

 which these cold masses of air offer to the 

 attempt (in the end futile) of the upper air to 

 steer them round the pole from west to east. 

 If left to themselves they would circulate in 

 opposition to the circulation of the upper air 

 with which they are in x)erpetual conflict. 



With regard to tropical revolving storms. 

 Dr. Shaw holds that these must be considered 

 under a different head, namely that of turbu- 

 lent motion, and intimates that papers are 

 forthcoming on this subject. 



The third paper is largely made up of tables 

 for facilitating computation in problems like 

 those referred to above. 



In the fourth paper our author deals with 

 examples taken from typical cases of atmos- 

 pheric structure selected by Mr. Cave for illus- 

 tration by means of photographs of models in 

 the " Structure of the Atmosphere in Clear 

 Weather." Five distinct classes are considered. 

 He introduces a new conception, that of 

 operative pressure. How this is produced does 

 not appear but if its existence be granted and 

 the thermal structure of the underlying air, 

 then the deductions drawn follow with mathe- 

 matical precision. Instances of irregular dis- 

 tribution of temperature are explained and in 

 the case of one marked inversion it is imag- 

 ined that the construction was formed above a 

 pool of cold air such as would be found over 

 fog. The result of recent work is to show 

 that as regards the weather of the present and 

 the immediate future, the operative pressure 

 distribution and the thermal structure of the 

 atmosphere between it and the ground ought 

 to be regarded as independent variables. 



Shaw looks forward to the issue of maps of 

 the upper levels wherein cloud observations 

 and pilot balloon data will show what the 

 actual circulation at a given level is. From 

 these we may estimate the effect on pressure 

 distribution in lower levels. 



The papers taken together give a working 

 plan so far as general atmospheric motion is 

 concerned and form a distinct contribution to 

 the solution of the problem of the life-history 

 of cyclones and anti-cyclones. 



Alexander McAdie 



Blue Hn,L Meteorological Observatoet 



NAVIGATION WITHOUT LOGAMITHMSt^ 

 Captain Guyou, of the French navy, a 



mathematician of note, author of valuable 

 1 ' ' Nouvelles Tables De Navigation, ' ' Emile 



Guyou. Berger-Levrault, Editeurs, Paris. 



