FUTURE HABITABILITY OF THE EARTH CHAMBERLIN. 373 



implied a partition from a rotating mass, and so a genesis from a 

 gaseous or quasi-gaseous body was almost universally accepted as by 

 compulsion. 



Starting as a gaseous globe, an early passage into a molten sphere 

 wrapped in a hot vaporous atmosphere was logically assigned the 

 earth. The atmosphere was made vast to contain all the water of 

 the globe and the volatile matter that the heated conditions were pre- 

 sumed to have generated. At a later stage a crust was assigned to 

 the cooling globe, and the waters, condensing on this, gave the infant 

 earth the swaddling bands of a universal ocean. On further cooling, 

 shrinkage and deformation were supposed to follow, the waters to 

 be gathered into basins, the land to appear, and the formation of 

 earth strata to begin. 



It is important to note that the main agency in this hypothetical 

 history was the loss of heat, and so, with logical consistency, loss of 

 heat was made to lie at the bottom of the great events of the earth's 

 history down to the present time, and, in framing a forecast of the 

 future, loss of heat was made the chief cause of the earth's prospec- 

 tive doom as a habitable planet. The whole history was interpreted 

 as a stupendous declension. From a plethora of heat at the outset 

 loss followed loss till our semiglacial stage has come, and, by proph- 

 ecy, loss is to follow loss in the future till the final winter shall come. 

 Starting with a plethora of air and water swaddling the earth, loss 

 followed loss till our emaciated stage has been reached, and loss is 

 to follow loss till drought shall join frigidity in marking the final 

 state and the end of all life. The details of this inherited picture 

 were not wanting. As the body of the earth cooled and shrank, the 

 waters were permitted to enter it and by union with its substance 

 lose their fluid state. In like manner the air, entering the earth 

 and uniting with it little by little, depleted the smothering atmosphere, 

 lessened its oppressive weight, tempered its noxious nature until 

 it was compatible with low life, and later with higher life, and at 

 length brought it down to the present state. Projected into the 

 future, the forecast tells of further depletion, with the pauperiza- 

 tion and at length the extinction of life. 



The shrinking of the oceans more and more into the deep basins, 

 the absorption of the waters into the body of the earth, and the pro- 

 gressive cooling and emaciation of the air were logically supposed 

 to join in progressively reducing the vapors that rose from the 

 waters. At first, hypothetically, a deep warm mantle of cloud clothed 

 the whole earth, and this shroud was thought to persist halfway down 

 the geologic ages, giving sultry, lowering climates in all latitudes. At 

 length, however, this mantle was pictured as giving place to rifted 

 clouds and clearer skies, and still later to mild aridities, to be fol- 

 lowed in turn by desert stages, and these, growing apace, led on to 



