Mr J. Sang on a Systematic Method of 



tern, was communicated to me many years ago by my brother 

 Mr Edward Sang. I have since then been constantly engaged 

 in a business, which has induced me to extend and arrange the 

 system, and which has afforded many opportunities of subject- 

 ing the arrangements to the test of experience. 



To one whb has glanced over the laws which connect 

 form of outline with surface and capacity, it would appear a 

 matter of no difficulty to discover the extent of any portion of 

 ground ; and it would seem to be of no consequence by which 

 of them we were to be guided. There are, however, in the na- 

 ture of the tools employed, and of the surface operated on, as 

 well as in the constitution of our own senses, many obstacles to 

 the application of these laws. And as those for whose conve- 

 nience measurements of ground are made, cannot be supposed 

 acquainted with these minutia3, so as to have a preference to 

 one system over another, I shall first point out, in as few words 

 as possible, the common methods, and their defects. 



Ground is usually measured by dividing it into trigons and 

 trapezoids, whose dimensions are ascertained by a chain alone, 

 or by a chain accompanied by an instrument for measuring 

 angles. ' The trigons always occupy the interior and larger part 

 of the ground, while the trapezoids are arranged on the out- 

 skirts, and fill up the surface between the trigons and the boun- 

 dary of the ground, in a manner similar to that in the annexed 

 figure. The parallel sides of the trapezoids are technically 



