558 The Account of a 



depressed, a peg was driven into the ground, with its centre 

 nearly under the cross wires ; after which, a pin was moved on 

 the surface of the peg, as directed by a person looking through 

 the telescope, till it came to that point at which it bisected the 

 angle formed by the cross wires. The measurement was then 

 carried on, in this new direction, a space of 10. chains, at the end 

 of which, the same operations were repeated, and the old direc- 

 tion pursued. It does not seem probable, that an error amounting 

 to more than ~ of an inch, can have resulted from this pro- 

 cedure. 



King's Sedgemoor being sufficiently level, the base was 

 measured horizontally; an advantageous circumstance; but, 

 from the soft texture of the soil, the pickets could not be driven 

 into the ground so firmly as to be without some small degree 

 of motion, in case a person stood close to them. Therefore, 

 those who attended the handles of the chains, either used long 

 stools, or placed themselves so as to divide the pressure>arising 

 from the weights of their bodies equally on each side of the pickets. 

 The disturbances to which the register-heads were liable, did 

 not discover themselves till a mile of the base had been mea- 

 sured ; and, although it became probable that small errors only 

 had resulted from the want of those precautions we afterwards 

 followed, yet we considered what we had done as erroneous, 

 and recommenced the measurement, with the advantage of 

 experience. At present, I shall content myself with observing, 

 that due attention was paid to all necessary minutiae in this 

 measurement, and refer those who are desirous of being more 

 particularly informed, to the Philosophical Transactions for 

 1795, as the mode of proceeding on the present occasion was 

 perfectly similar to that on Hounslow Heath. 



