THE STORY OF NINETEENTH-CENTURY SCIENCE 



our knowledge of the condition of the telluric depths is 

 still far from definite. 



If so much uncertainty attends these fundamental 

 questions as to the earth's past and present, it is not 

 strange that open problems as to her future are still 

 more numerous. We have seen how, according to Pro- 

 fessor Darwin's computations, the moon threatens to 

 come back to earth with destructive force some day. 

 Yet Professor Darwin himself urges that there are ele- 

 ments of fallibility in the data involved that rob the 

 computation of all certainty. Much the same thing is 

 true of perhaps all the estimates that have been made 

 as to the earth's ultimate fate. Thus it has been sug- 

 gested that, even should the sun's heat not forsake us, 

 our day will become month-long, and then year-long; 

 that all the water of the globe must ultimately filter 

 into its depths, and all the air fly off into space, leaving 

 our earth as dry and as devoid of atmosphere as the 

 moon ; and, finally, that ether-friction, if it exist, or, in 

 default of that, meteoric friction, must ultimately bring 

 the earth back to the sun. But in all these prognosti- 

 cations there are possible compensating factors that 

 vitiate the estimates and leave the exact results in 

 doubt. The last word of the cosmic science of our 

 century is a prophecy of evil if annihilation be an evil. 

 But it is left for the science of another generation to 

 point out more clearly the exact terms in which the 

 prophecy is most likely to be fulfilled. 



