RETOllT ON A LJEVKL LINE. 11 



of these scales with regard to a level surface. We may in this 

 manner, and in no other, learn the true form of the ocean at any 

 time ; besides the practical advantages, which, as I have said, 

 would flow from having standard levels in various parts of the 

 island. I may mention, that the kingdom of the Netherlands 

 already possesses such a system of levels, by which all points of 

 its surface are referred to a certain zero at Amsterdam. 



Whether such an extension of the level line measured for the 

 Association be desirable, may best be determined by the Com- 

 mittee of the Physical Section. In the mean time I trust that what 

 has already been done possesses no small value, being, so far as I 

 am aware, the first attempt of the kind, executed with great care, 

 and I see every reason to think, with great accuracy. 



22. The following are the heights of the marks above the zero 

 point. 



Feet. 



Iron bar at Portishead Fort 102-5795 



Temporary mark at Wick rocks (Station N° 810) . . 99*4833 



Copper bar in granite block, Axmouth 83*6513 



Copper bar in Axmouth church 89*53 18 



Copper bar in Uphill church. (This is not yet insert- 

 ed. The + cut on the east end of the church is at 



the height) 205*8305 



Copper bar at Perry Farm, East Quantockshead . . 244*4365 



Copper bar at Stolford 125*1114 



Level of mean water at Portishead 72*69 



Wick rocks ...... 73'11 



Axmouth 71*96 



Account of the Leveling Operations between the Bristol 

 Channel and the English Channel, hy Thomas G. Bunt. 



Previously to my commencing the leveling which I had re- 

 ceived instructions from Professor Whewell to undertake on 

 account of the British Association, I was desirous of deriving 

 such assistance as might be obtained from any published account 

 of a similar enterprise, in which due attention had been paid to 

 the niceties which the operation requires, and the best means 

 for ensuring accuracy ascertained and pointed out. All the or- 

 dinary treatises on leveling are of the most elementary and su- 

 perficial kind ; and the only account I have met with which could 

 at all assist me is that given by Captain Lloyd in the Philoso- 

 phical Transactions for 1831, which details with clearness, and 



