804 



SCIENCE 



[N. S. Vol. XLII. No. 1092 



What the thermodynamic computations do 

 show, however, is that the solar effect on the 

 atmosphere above 35,500 m. is nearly as great 

 as that on the lower layers; and this is a fact 

 of very great importance. 



The terms " absorption " and " transmission,'' 

 as applied to the derivation of atmospheric 

 free heat from the sun's rays on page 377, have 

 apparently been transposed, but are correctly 

 applied as regards terrestrial radiation. This 

 follows because Q is the free heat "trans- 

 mitted " in a way within the layer, but it is 

 obtained by absorpiion of radiation and is pro- 

 portional to such absorption, other things being 

 equal. 



The atmospheric heat on which depends the 

 internal radiation of the atmosphere J a, given 

 for each 1,000 meters, is equal to the change 

 in its radiant potential \K, and is due to 

 absorbed terrestrial radiation. The curve of 

 the change of density with the altitude agrees 

 with that of the Ja function, showing that the 

 expansile force of the air, or that force which 

 gives its adiabatic expansion, is wholly gov- 

 erned by the mechanism of internal radiation 

 between the air molecules. /„ is largest at the 

 ground surface and progressively diminishes 

 to the outer limit of the atmosphere. The 

 free heat {Q), on the other hand, is distinct 

 from Ja and is wholly devoted to expanding 

 the air above the adiabatic rate. While the 

 summations of the two from the surface to 

 about 31 km. are very nearly equal, their dis- 

 tribution is quite different. Q is very small in 

 the lowest layers and increases upward, but 

 with wide Cuctuations. In a general way Q 

 follows the fortunes of the incoming solar 

 rays, and while it may not be wholly dependent 

 on their absorption, it appears to be very nearly 

 so. There is no evidence that the curve of 

 density agrees with the solar radiation at 

 every level, as is asserted in Chapter VII. 



If the air radiated like a black body, the 

 radiation /„ of any layer could be computed 

 from the temperature by Stefan's Law. 

 Summed, layer by layer, for the air column up 

 to 50 km., 2(/„., — /„ J = — 381.81, while 

 ^(Ja-i — =^a-o)=' — 136.75, or the air radiation 

 is about one third that of a black body. The 



figures, as thus stated, denote a thermal trans- 

 ference of so many gram calories per minute 

 within a volume of five million cubic centi- 

 meters, and are derived from Bigelow's com- 

 putation after correcting for the erroneous 

 transformation factor; but they lend no sup- 

 port to his curious conclusion that air radiates 

 six times better than the black body. 



The pyrheliometric method for finding the 

 solar constant which is described in Chapter V., 

 is further extended and modified in Chapter 

 VII., pages 388 to 394. This method is finally 

 admitted to be discredited by experience, 

 though its author does not recognize why this 

 is so. A new and entirely different method 

 of discussing pyrheliometric data is then devel- 

 oped (pp. 394 to 401) which, though empirical, 

 appears to eliminate the influence of water 

 vapor and altitude in the general means very 

 well, making it possible to compare winter 

 observations with summer, and also to deter- 

 mine a station correction to sea level. In this 

 method the erroneous data derived from in- 

 correctly interpreted thermodynamics are 

 abandoned. The extrapolation of the resulting 

 curve (A, Fig. 76) gives solar radiation ^ 3.22 

 at the height for which the writer's reduction 

 of Violle's high-level observation gave 2.86 

 gram cal./cm.^ min. ; and thus it appears prob- 

 able that the value which Bigelow adopts for 

 the solar constant (3.95) should be reduced to 

 3.6 gram eal./cm.^ min. A similar result fol- 

 lows from the writer's interpretation of the 

 thermodynamic argument. 



The formula for the mass of aqueous vapor 

 in the upper air (pp. 342 and 373) is both 

 complicated and erroneous. It gives a value 

 about three times too large at 10,000 meters, 

 ten times too large at about 24,000 meters, and 

 increasingly greater at still higher altitudes. 



The author's faith in the virtues of a formula 

 is seen in his publication of some columns of 

 figures which make such well-recognized con- 

 stants as the mass of a hydrogen atom and the 

 charge on an electron, variable. There are a 

 few minor mistakes, such as the conversion of 

 the charge on an electron through the use of 

 an erroneous dimensional formula, but these 

 will be readily recognized. 



