PREPARATION OF THE DESIGN 75 



sion which might cause all the measurements to be 

 useless. There are many ways of tackling a com- 

 plicated piece of ground, and not two persons 

 would set to work on the same lines. In schem- 

 ing the work aim to have at least one line the 

 full length of the ground ; make all as long as 

 possible ; and avoid taking the tape through 

 shrubberies or high herbaceous borders. The 

 position of minor features can often be determined 

 simply by noting that as the tape lay such an 

 object was, say, 3 ft. away from the line at 142. 

 Before lifting the tape all possible information 

 should be taken from it. The preliminary sketch 

 may have to be supplemented by enlarged details 

 for which space should be left at the side of the 

 paper. The positions of trees, and other separate 

 features are found by making the object one of the 

 three corners of a triangle, of which the two other 

 corners are known through other measurements 

 on the survey. The commonest failure in a survey 

 is caused by thinking a point is located because it 

 has two measurements relating to it, whereas they 

 may be valueless from being taken from points 

 whose positions have not been found. A careful 

 attention to the preliminary scheme is the best 

 safeguard against such errors. 



Practice in surveying leads to a confident dealing 

 with awkward corners and obstacles. Water is 

 the most serious obstacle as it is impossible to 

 get the tape across an arm of a lake, a bend of a 



