EXTRACTS FOREIGN AND DOMESTIC. 137 



the observations to be made at the mean tide level ; respecting 

 the oscillations of this part of -North America. The rise and fall, 

 of a great part of the coast of Scandinavia has been observed by 

 Swedish geologists and noted. And it is now pretty certain that 

 no part of the earth's surface is stationary. 



I Prof. Silliman. — I should like to add inquiry into a subject lam 

 ignorant of and have no means of informing myself about. It is 

 the average elevation of continents above the level of the sea. 



I. The average elevation of North America ; 

 1 II. Tlie average elevation of South America ; 



III. The average elevation of Europe ; 



IV. The average elevation of Asia ; 

 V. The average elevation of Africa. 



Jy the deduction of particulars from known data we can come 

 retty nearly to correct data. 



Prof. Rogers. — HumboUt has published data about the mean 

 evel of certain lands. He gives the mean level of Asia 800 feet 

 bove the ocean ; and it is astonishing how small a part the 

 lountains have to contribute to the earth's elevation. 



Silliman. — What does he give, sir, as the elevation of North 

 Llherica ? 



Rogers. — Some five or six hundred feet as the average. 



Silliman. — That is even within my mark ; I have said less than 

 quarter of a mile, and then have been thought romancing; and 

 ven this may be caused by the mass of the earth swelling by ex- 

 anslon. 



Rogers. — By probably the general wavering of the earth's crust, 

 weden rises several feet a century ; and it w^ould not take long to 

 ing all Europe to its present level. 



Prof. Loomis. — The pilots of Maine say that the tide is sinking 



ery year ; and that certain rocks on Maine shore are now visi- 

 e, over which they could formerly conduct vessels at any tide. 



is so especially at the mouth of the Kennebec. 



Prof. Rogers observed that the north shores appeared to be going 



iwn and the south coming up ; else why were all our south shores 

 dy flats, and New-England a rock -bound coast from Cape Cod 



its north-east border. The middle and southern States — all the 

 :a islands from Long-Island to the Florida Keys, indicate a gene- 



1 rise of the land south. This Cojitinent is swinging on a hinge 

 ( great pivot, the point of which is at about the Bay of Massachu- 

 !tts. The south part is rising and the north going down ; not 

 »actly in their moral or intellectual qualifications, unfortunately, 

 < recent changes indicate. (Laughter.) 



Prof. Silliman. — Where did you put your pivot sir ? (Laugh- 

 '■) 



Prof. Rogers. — About Cape Cod I think it is fixed. (More 

 1 i2;hter, 



VOL. II. — xo. I. S 



