PREPARATION OF THE DESIGN 69 



DIAGRAM 17. 



veys, where the measuring of straight lines is 

 difficult or tedious. Any method involving the 

 measurement of angles requires special instruments, 

 and considerable after calculation, whereas it is 

 perfectly simple to work out a triangle of which 

 the length of the sides are known, and a tape 

 and stakes are sufficient for its survey. 



Suppose a plot 

 of land enclosed 

 by a fence (Dia- 

 gram 18). Make 

 a rough drawing 

 of the ground, and 

 mark the corners 

 A B C D, in order 

 to have a simple 

 means of record- 

 ing the measure- 

 ments taken. 

 Measure along 

 AB, BC, CD and 



D A respectively, and record the length on the 

 sketch plan, and then cornerwise from D to B. This 

 makes a survey in its simplest form, being within 



DIAGRAM 18. 



