i 9 4 TEE POPULAR SCIENCE MONTHLY. 



witb the earthquake-shocks and slight movements of depression which 

 have occurred in North America. It is possible that these slow and 

 secular movements may go on uninterruptedly until considerable 

 changes are produced ; but it is quite as likely that they may be re- 

 tarded or reversed. It is possible, on the other hand, that after the 

 long period of quiescence which has elapsed there may be a new settle- 

 ment of the ocean-bed, accompanied with foldings of the crust, espe- 

 cially on the western side of the Atlantic, and possibly with renewed 

 volcanic activity on its eastern margin. In either case a long time 

 relatively to our limited human chronology may intervene before the 

 occurrence of any marked change. 



On the whole, the experience of the past would lead us to expect 

 movements and eruptive discharges in the Pacific rather than in the 

 Atlantic area. It is therefore not unlikely that the Atlantic may re- 

 main undisturbed, unless secondarily and indirectly, until after the 

 Pacific area shall have attained to a greater degree of quiescence than 

 at present. But this subject is one too much involved in uncertainty 

 to warrant us in following it further. In the mean time the Atlantic 

 is to us a practically permanent ocean, varying only in its tides, its 

 currents, and its winds, which science has already reduced to definite 

 laws, so that we can use if we can not regulate them. It is ours to 

 take advantage of this precious time of quietude, and to extend the 

 blessings of science and of our Christian civilization from shore to 

 shore until there shall be no more sea, not in the sense of that final 

 drying-up of Old Ocean to which some physicists look forward, but in 

 the higher sense of its ceasing to be the emblem of unrest and disturb- 

 ance and the cause of isolation. 



I must now close this address with a short statement of the general 

 objects which I have had in view in directing your attention to the 

 geological development of the Atlantic. We can not, I think, consider 

 the topics to which I have referred without perceiving that the history 

 of ocean and continent is an example of progressive design, quite as 

 much as that of living beings. Nor can we fail to see that, while in 

 some important directions we have penetrated the great secret of Na- 

 ture in reference to the general plan and structure of the earth and its 

 waters and the changes through which they have passed, we have still 

 very much to learn, and perhaps quite as much to unlearn, and that 

 the future holds out to us and to our successors higher, grander, and 

 clearer conceptions than those to which we have yet attained. The 

 vastness and the might of Ocean, and the manner in which it cherishes 

 the feeblest and most fragile beings, alike speak to us of Him who holds 

 it in the hollow of his hand, and gave to it of old its boundaries and 

 its laws ; but its teaching ascends to a higher tone when we consider 

 its origin and history, and the manner in which it has been made to 

 build up continents and mountain-chains, and at the same time to 

 nourish and sustain the teeming life of sea and land. 



