1 882. 81 Trans, N. V. Ac. Uz, 



from the earth, and after the cooling of the globe had produced the 

 precipitation and accumulation of ocean waters, the attraction of the 

 moon acting inversely as the cube of the distance, produced tides of 

 stupendous altitude as compared with any now witnessed. For exam- 

 ple, supposing the earth to have been largely covered with water, when 

 the moon was 40,000 miles away, one sixth of its present distance, its 

 attraction must have been thirty-six times as great as at present, and 

 its efficiency as a tide-producer two hundred and sixteen times as great 

 as at present. This would give, for an average tide corresponding to a 

 tide of three feet now, a height of 648 feet. 



Prof. Ball pictures to his audience the effect of a tidal wave of this 

 height rushing over and retreating from all shores twice in each 

 short day, and jusiy ascribes enormous destructive power to such an 

 agent. This condition of things he fancies to have existed forty or fifty 

 millions of years ago, perhaps when the first sedimentary rocks now 

 known, the old Palaeozoic and Archaean strata, were deposited ; and since 

 in certain localities there were accumulations of mechanical sediments, 

 shales, sandstones, etc., to the depth of several miles in these ages, 

 they are explained to be the result of the action of these tremendous 

 tides. 



Prof. Ball further ascribes to this agent the greater part of the 

 changes that have taken place on the earth's surface, and claims to 

 have revealed to geologists in this discovery the most important factor 

 in all their data for writing the ancient history of the globe, and one of 

 which they seem to have been strangely ignorant. 



Now, all this is exceedingly interesting, and important. I'f true; but 

 in behalf of the geologists, I venture to report certain facts which seem 

 to be quite irreconcilable with it. There can be no question that a 

 tide of 600 to 1000 feet in height, sweeping over all shores and lowlands 

 twice a day, would be a most powerful destructive and creative engine ; 

 and it may be conceded at once that its potency in remodeling the 

 earth's surface would far surpass any agent of change now in action. 



Let us imagine for a moment what the effect of a tide two hundred 

 times greater than the present would be, if called into existence on the 

 Atlantic coast of America to-day. The height of the tide along our 

 coast vaiies from nine to twelve feet, and we may say the average is 

 ten. This would give a height of two thousand feet to the tide pro- 

 duced by the moon if only 40,000 miles distant. The effect of such a 

 flood would be so tremendous that it can hardly be realized. The whole 

 littoral plain, two hundred miles wide, which forms the topographical 

 margin of the continent, now half sub-marine, half sub-aerial, would be 

 swept twice a day with a wave not less than a thousand feet in height • 

 and a bore fifty times as high as that of the Hoogly would rush up the 



