Decembeb 31, 1909] 



SCIENCE 



939 



the earth stretches back not merely for 

 thousands but for millions and tens of mil- 

 lions of yeai-s; that the on-goingrs of the 

 earth are actuated by energies too broad 

 and deep and strong to be swerved in their 

 course or brought to an end by the acts 

 of those who dwell upon it ; that the march 

 of earth-history has a mighty tread not to 

 be measured by the merits or lapses of 

 even our favored race. 



The trend of prophetic thought in the 

 last century invites a closer review. The 

 basis of forecast lay fundamentally in the 

 mode of origin assigned the earth and in 

 the general trend of its past history, espe- 

 cially the trend of those agencies that con- 

 trolled the conditions of life on its surface. 

 The solar system was thought to have had 

 its origin in a gaseous or quasi-gaseous 

 nebula. The earth, as a member of the 

 solar system, partook of this origin, and 

 ■was conceived to have been, at an early 

 stage, itself a fiery, gaseous globe. It is 

 not needful here to review the special 

 hypotheses or pay honor to their great 

 authors from Kant and Laplace to Lockyer 

 and Darwin, for the sole feature that po- 

 tentially shaped the history of the earth 

 was the early gaseo-molten state in which 

 they essentially concurred. An alterna- 

 tive was indeed offered in the suggestion 

 that the earth might have gi-own up by the 

 accretion of small bodies but it was then 

 held by students of dynamics that such an 

 origin was inconsistent with the symmetry 

 of the system and the rotations of the 

 planets, and so an origin in the gaseous or 

 quasi-gaseous form was almost universally 

 accepted, as by compulsion. Later, the 

 gaseous earth, by cooling and condensing, 

 was thought to pass into a molten sphere 

 wrapt in a hot vaporous atmosphere. This 

 atmosphere was vast because the condi- 

 tions required it to contain all the water 

 of the globe and all the volatile matters 

 that have since entered into the waters and 



the body of the earth. At a later stage a 

 crust was logically made to form over the 

 molten sphere and the waters to condense 

 upon it, swaddling the entire globe per- 

 haps in a universal ocean. By further 

 cooling, shrinkage and deformation, the 

 waters were thought to be drawn into 

 basins, the land to appear and the history 

 of the stratigraphic record to begin. It is 

 important to note that the main agency in 

 this hj-pothetical history was loss of heat; 

 and so, with consistent logic, loss of heat 

 was made to lie at the bottom of the great 

 events of the earth's subsequent history 

 and, in the forecast, to be the chief cause 

 of its doom. From a plethora of heat, of 

 air and of ocean, putative loss followed 

 loss in the past, and by prophecy loss is to 

 follow loss in the future until emaciation, 

 drought and frigidity mark the final state 

 and the end of all life. As the body of the 

 earth cooled and shrank and permitted 

 penetration, the ocean was made to enter 

 it and by union with its substance was 

 thought to have been suffering loss in the 

 long past and to be doomed to further 

 losses yet to come. By a like union of the 

 constituents of the air with the body of 

 the earth, as time went on, the great 

 smothering atmosphere of the primitive 

 days was supposed to be brought down 

 first to compatibility with marine life, 

 later to the lower land life and still later 

 to the higher air-breathing forms. Pro- 

 jected logically into the future, still 

 further depletion of the vital constituents 

 even to the verge of exhaustion, attended 

 with pauperization and finally with ex- 

 tinction of life, entered into the forecast. 

 With the gathering of the oceans more and 

 more into the basins and their absorption 

 into the body of the earth, with the persis- 

 tent consumption of the atmosphere and 

 with the progressive cooling of the whole, 

 the moisture of the air was thought also to 

 have grown less and less. At first a deep, 



