2 EIGHTH REPORT — 1838. 



twenty feet lower on some parts of the coast of England than 

 on oUiers. And although men of science hav£ very generally 

 seen the pi'opriety of taking mean ivaler, (the mean of low and 

 high water,) for the level of the sea, this selection, till confirmed 

 by some actual observations of facts, might appear arbitrary and 

 insecure. But if it be found that the mean water is at the same 

 level at different and distant points of the coast, where the low' 

 water is at different levels, the propriety of taking mean water 

 for the level of the sea will probably be generally acknow- 

 ledged. 



It may be observed, moreover, that the question of the per- 

 manence or change of the height of any point of the coast (un- 

 connected with a system of interior leveling) cannot be de- 

 cided by observation, except by reference to the level of the sea ; 

 and therefore to determine what is the level of the sea is im- 

 portant also to the geologist. On coasts where there are tides, 

 the question of the stability of the land involves the question of 

 the laws of change of the water. 



2. For these reasons it was considered desirable to ascertain 

 by careful and exact levelling the relative heights of certain 

 points of the coast of England, and to refer these points to the 

 sea by adequate tide observations. The British Association at 

 its meeting in 1834, voted a sum of money (500/.) to be em- 

 ployed upon this object, and appointed a Committee to decide 

 upon and direct the requisite operations. The same thing was 

 done at the subsequent meeting in 1835. But the difficulty of 

 fixing upon a plan of operations and of selecting the means of 

 carrying it into effect by a joint deliberation of a large Com- 

 mittee scattered over thewhole empire, prevented anyactive steps 

 being taken towards the attainment of the object. At the meet- 

 ing at Bristol in 1836, in order to remedy this inconvenience, 

 those members of the Committee who had the opportunity of 

 conferring with each other after the separation of the Association 

 took upon themselves the task of directing the execution of the 

 plan. And it appeared to them desirable that a person should 

 be selected to perform the leveling operation for the Associa- 

 tion, independently of any other surveys which might be going 

 on ; for no materials collected for the purpose of any other sur- 

 vey could, in accuracy and other conditions, answer the purposes 

 contemplated by the Committee. They considered themselves 

 fortunate in being able to engage Mr. Bunt oi Bristol in this ser- 

 i^ice, having entirely satisfied themselves of his accuracy and 

 scrupulousness in observing, and of his clear apprehension of 

 the nature of the operation. They also took the precaution of 

 directing Mr. Bunt to execute a preparatory level from Bristol 



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