Bkcembek 31, Hion] 



SCIENCE 



947 



which life is depeudent, there has been, 

 through the known ages, vast as they are, 

 an oscillatory movement which has brought 

 profound changes again and again but has 

 never permitted any of the disasteis 

 threatened in these movements to go far 

 enough to compass the universal extinction 

 of life. These reciprocal movements ap- 

 pear to be dependent upon a balancing of 

 the action of agencies that is scarcely less 

 than a law of equilibrium. It is not too 

 much to regard this as a regulative sys- 

 tem. A clear insight into the agencies of 

 this regulative system is rather a task of 

 the future than an attainment of the pres- 

 ent, and I can only offer tentative hints 

 of what may prove to be its main factors 

 and beg of you to accept them with due 

 reserve. 



The preservation of the land against 

 the incessant encroachments of the waters 

 seems probably due to a periodic deforma- 

 tion of the earth-body dependent on in- 

 ternal dynamics not yet well understood, 

 at least not yet demonstrated to general 

 satisfaction. The body of the earth feeds 

 its atmosphere through volcanic and other 

 means. How far this is merely a return 

 of what has been absorbed earlier it is not 

 prudent here to say, as opinion is not har- 

 monious on this, and the evidence is as yet 

 uncertain. Jluch depends on the constitu- 

 tion of the earth's interior and that in 

 turn hinges on its mode of origin. Per- 

 haps it will be agreed generally that feed- 

 ing from the interior is one of the .sources 

 of supply which offsets the depletion of 

 the atmosphere caused by its union with 

 earth substance, in short that the earth- 

 body gives out as well as takes in atmos- 

 pheric material. Important or unimpor- 

 tant as this may be, it is not apparent that 

 there is in it any automatic balancing 

 suited to control the delicate adjustments 

 requisite for continuity of life. The ocean 

 acts as an important regulator by alter- 



nately absorbing and giving out the at- 

 mospheric gases as required by the state 

 of equilibrium between the water and the 

 air. This. action is automatic but has its 

 limitations and peculiarities and does not 

 seem wholly adequate. If we are able to 

 name such an adequate automatic action at 

 all at present, it probably lies in the molec- 

 ular activities of the terrestrial and solar 

 atmospheres and in the relations of these 

 to the gi'avitative powei*s of the earth and 

 the sun. 



If analysis of the molecular action of 

 the outer atmosphere be pushed to its 

 logical conclusions, it leads to the concep- 

 tion of supplementary atmo.spheres, in 

 part orbital, filling, in their attenuated 

 way, the whole sphere of the earth's gravi- 

 tative control. A similar study of the 

 sun's atmosphere suggests a similar sup- 

 plementary extension and this extended 

 portion surrounds and embraces the earth 's 

 atmosphere. Under the laws of molecular 

 activity these two atmospheres must be 

 interchanging molecules at rates dependent 

 on the conditions of equilibrium between 

 them. It is reasonable that an excess in 

 the earth's atmosphere should cause it to 

 feed out into the sun's sphere of control 

 more than it receives, and that a deficiency 

 in the earth's atmo.sphei-e should cause 

 more feeding in f i-om the sun 's .supplemen- 

 tary atmospheres than the earth gives out. 

 If this conception be true and be efficient, 

 the maintenance of the delicate atmos- 

 pheric conditions required for the con- 

 tinuity of life is automatically secured. 

 The failure of our atmospheric supply is 

 thus made to hang, not simply on the 

 losses and gains at the earth's surface, but 

 on the solar interchange and hence on the 

 solar endurance. 



The sun is giving forth daily prodigious 

 measures of energj'. The endurance of the 

 sun is not, however, merely a question of 

 unrequited loss, for it gains energy and 



