6 
Table 3. The calculated mean error for the different field workers. All series 
assembled. 
/ 
n = number of points. m p = ± y — ^ in meters. 
Field worker 
Sparse vegetation 1) 
Dense vegetation 2) 
n 
m P 
n 
m P 
A 
279 
2.74 
445 
3.39 
F 
187 
2.98 
265 
3.47 
N 
272 
2.66 
228 
3.47 
Average 
246 
2.78 
313 
3.40 
Remarks: (') The greatest m p = 3.22 for field worker F, 1:15.000 normal angle — 4 field 
workers. The least m p = 2.34 for field worker A, 1:15.000 wide angle — 
3 field workers. 
( 2 ) The greatest m p = 4.33 for field worker N, 1:20.000 wide angle 1 field 
worker. The least m p = 2.99 for field worker F, 1:15.000 wide angle — 
2 field workers. 
Table 4. The calculated mean error for the different ground surveys. Series and 
field workers grouped together. 
n = number of points. m p = + y in meters. 
Work in the field (In succession) 
Sparse vegetation 
Dense vegetation 
n 
m P 
n 
m P 
1 
171 
2.88 
212 
3.70 
2 
177 
2.97 
238 
3.41 
3 
169 
2.55 
261 
3.31 
4 
221 
2.80 
227 
3.30 
The results of the experiments. 
The material for the error class I is divided into two main groups: 
(a) Visible signals in the control series. 
(b) Invisible signals in the control series. 
Each of these is divided into 2 sub-groups: 
Sparse vegetation: the ground round the boundary point can be seen. 
Dense vegetation: thickly wooded area.