Apeil 1, 1921] 



SCIENCE 



311 



260°. There is a scale wliicli might have been 

 advantageously used here, namely the Kel- 

 vin-Kilograde scale. True, few are as yet 

 familiar with it; but the colors should always 

 be in advance of the line, not abreast nor yet 

 behind. In an up-to-date scientific book we 

 have the right to expect leadei-ship rather 

 than tolerance. 



The airman has got to forget the unscien- 

 tific, arbitrary scales of his fathers; and stop 

 using inches, minus signs, etc. His range of 

 temperature is from summer day surface 

 values to winter sub-polar readings near the 

 stratosphere; and old-fashioned methods are 

 inadequate. 



Pressures are generally given in this book 

 in millimeters of mercury with occasional 

 lapses into inches. In a treatise dated 1920, 

 one might look for pressure values through- 

 out in units of force, that is, dynes or kilo- 

 dynes per square centimeter. 



In the chapter on " Atmospheric Circula- 

 tion " which is well put, and more clearly 

 explains the mechanics of deflection than most 

 other text-books, it is demonstrated that in 

 the case of a wind with a velocity of 22 meters 

 per second, there will be a modification of 

 velocity, depending upon whether the wind is 

 blowing east or west; that is, a given mass 

 weighs less going east than going west. A 

 note might have been added giving results of 

 recent gravity determinations at sea on fast- 

 moving (22-knot) destroyers (25-mile-per-hour 

 vessels) ; in which it was definitely ascertained 

 ihat the barometric pressure changed 0.1 

 kilobar (0.0Y5 mm.) when the course was 

 reversed. Going east with the earth the 

 centripetal force is greater than when steam- 

 ing west. All this is of importance in con- 

 nection with fast-moving airships.'- 



The discussion of change of velocity with 

 latitude, deflective effect of the earth's rota- 

 tion, relative values of centrifugal and rota- 

 tional components, and gradient winds, is 

 thorough and well expressed. Of course, the 

 explanation of friction acting as the effective 

 damping factor against high rotational winds 



1 See Science, February 6, 1920; also January 

 9, 1920. 



is no longer tenable; and there is not sufficient 

 emphasis laid on the fact that the high rota- 

 tive values are hypothetical, not real so far as 

 mobile air is involved. 



Chapter XL, on " Winds Adverse to 

 Aviation," explains the so-called " holes in 

 the air," " bumps," " dunts," etc. There is not 

 a mathematical symbol in the whole chapter. 

 The different phenomena are explained in 

 straightforward, simjjle language. However, 

 there is much yet to be learned in connection 

 with favorable and adverse conditions; and 

 we await some Mauiy who will do with the 

 logs of airships what the old Commodore did 

 with the logs of the clippers of his day. 



Chapter XIV. contains many photographs 

 of cloud forms, but neither here nor in the 

 first chapter where many instruments are 

 given, is mention made of a nephoscope. Fair 

 credit for cloud work done at Blue Hill Ob- 

 servatory is not given; nor is mention made 

 of Professor Bigelow's International Cloud 

 Report. 



Chapter XV., on " The Thunderstorm " has 

 105 pages, and yet is not included in Part II., 

 dealing with Atmospheric Electricity and 

 Auroras, which has only 18 pages. 



Part III., on " Atmospheric Optics," has 129 

 pages and is based largely on the well-knovm 

 Pernter-Exner " Meteorologische Optik " and 

 Mascart's " Traite d'Optique." 



Part IV., 74 pages, deals with factors of 

 climatic control, that is, in the author's words, 

 a discussion of the physics of climate and not 

 of its geographic distribution. The chief 

 factors considered are latitude, brightness of 

 the moon and planets, solar constant, solar 

 distance, obliquity of' ecliptic, perihelion phase, 

 extent and composition of the atmosphere, 

 vulcanism, sun spots, land elevation, land and 

 water distribution, atmospheric circulation, 

 ocean circulation, and surface covering. 



Elaborate tables of gradient wind velocities 

 are given in the appendix. "We notice a few 

 minor typographical errors. On page 136, 

 latitude 10°, the change of direction is 2°. 61 

 not 261, and the heading needs revising on 

 page 162, m.m. should be mm.; on page 221, 

 figure 31 should be 32 ; and on page 227, figure 



