164 THE CANADIAN SURVEYOR May, 1960 
TABLE II — ERRORS IN TERMS OF GROUND DIMENSIONS 
  
  
  
  
  
  
Flat area | Hilly area* Profile 
Instrument Specimen horizontal, | vertical, vertical, 
| variance meters | variance meters | variance meters 
- a. re EL fo | ral LR 
A-8 | ai. — 550 | — +1.2 
| 20 + 50 | 0.0 | —2.2 
| 25 + 55 | 0.3 —0.4 
| 27 +112 0.9 —0.7 
| 28 + 96 0.3 —2.3 
| 29 — 9 | 0.9 +0.1 
| 30 —171 | 0.1 +0.2 
mean -E rms | +22+100 | 0.5+0.12 | —0.6+1.4 
A-7 2 | + 80 | 1.2 —1.9 
6 | e | 0.1 —0.4 
9 — 282 | 0.0 | +0.4 
11 —123 0.8 | +0.6 
21 | —205 | 0.2 | 
| 26 | —405 | 0.3 | +1.9 
35 | — 415 | 0.0 | —i.7 
| —160 2-200 0.4+0.4 —0.2+1.5 
| 
C-8 22 | + 18 0.0 | —1.8 
| 23 | | 4.1 
| | 
Kelsh | 7 — 26 0.1 | -2.5 
10 149 0.5 | —0.8 
12 — 124 0.1 | —0.8 
14 —377 2.7 +0.6 
31 3 0.1 —0.4 
| 33 + 71 0.2 0.1 
| 34 —202 0.0 | 31 
| 38 | —429 | 1.4 | —0.4 
| H 1.9 | 2.6 
| es | sa 
| 1554176 | 081410 | —ooxi4 
Balplex 5 — 890 | 0.5 +4 .1 
8 — 565 1.0 —0.5 
4( —146 | 0.0 +3.2 
— 534 +360 0.5+0.5 +2.3+3.6 
*B factor of Table III. 
** Not used in computing mean. 
was not available. Measurements were made at 12 sections in order to have 10 values 
of all the 4... B terms. 
In general, all the tests proved to be considerably better than is normally obtained 
in productive work, which is understandable from the standpoint that each participant 
wanted to make a good showing. For example, one might be tempted to consider the 
standard vertical deviation of the Kelsh plotter as about 1 meter, corresponding to a 
U.S. c-factor of about 3800, inasmuch as the flight altitude was about 7600 meters. Of 
course this is a dangerous philosophy for practical productive operation. 
The discrepancies in the flat area were all quite large. The corresponding vertical 
discrepancy is normal, but the flatness of the area made the work difficult and inexact. 
The fact that little photographic texture was present in the flat cultivated fields prob- 
ably accounts for part of the difficulty.