REPORTS 



ON 



THE STATE OF SCIENCE. 



Account of a Level Line, measured from the Bristol Channel 

 to the English Channel, during the Year 1837-8, by Mr. 

 Bunt, imder the Direction of a Committee of the British 

 Association. Drawn up by the Rev. W. Whkwell, F.R.o. 

 one of the Co?nmittee. 



1 . At several of the meetings of the British Association it 

 was suggested, that the exact determination of the relative level 

 of three points considerably distant from each other on the coasts 

 of this island might throw Tight upon several important questions. 

 Such a determination, it was represented, might especially be 

 made subservient to the solution of the two important problems, 

 — how far the position of the earth's surface is permanent — and 

 what ought to be understood by " the level of the sea." For if, 

 as some geologists think, many parts of the earth's surface are 

 slowly changing their position, such a change is extremely dif- 

 ficult to prove or disprove by observations made at any one point. 

 But if three points were at one time determined to be in one 

 horizontal surface, and were at a subsequent period found to be 

 at different heights, their relative elevations at the second epoch 

 would not only establish the fact of a change in the position of 

 the earth's surface, but M'ould enable us to determine, by an easy 

 calculation, the angle through which this part of the surface had 

 been elevated, and the axis about which the elevation had taken 

 place. And with regard to the level of the sea, it is well known 

 that surveyors and naval men are in the habit of assuming the 

 surface of low water of spring tides to I'epresent this level. 

 Now not only is such a surface extremely indefinite (varying 

 very considerably with the parallax and declination of the moon 

 and sun) but it is not in fact, not even approximately, a level 

 surface at all. The level of the sea, thus determined, would be 



VOL. YII. 1838. J5 



