May, 1960 ANALYSIS OF CONTOUR ERRORS 161 
  
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RENFREW INTERNATIONAL TEST 
SCALE 1: 5000 
CONTOUR 125 
SURVEYED TACHEOMETRICALLY 
  
  
  
Fic. 1 
Washington, D.C. The records and computations are in the hands of the committee 
and have been inspected at the National Research Council of Canada. 
A. general view of the model area is contained in the accompanying report by Mr. 
T. J. Blachut, President of Commission IV-3. Drawings of the three test areas are 
shown in Figures 1, 2, and 3. The original compilation scales of test areas No. 1 and 
No. 2 are indicated on the drawings, but these scales were reduced to the map scale by 
photography onto transparent film positive. 
Several tables are compiled in an effort to convey the results to the reader. The 
tables are of two general categories: qualitative and quantitative. The qualitative 
comparison shown in Table I is very simple and indicates the relative rank of the 
various instruments without any effort to specify the absolute meanings of the numbers 
in terms of ground dimensions. They consist merely of the lists of the absolute (not 
algebraic) sums of the map departures of the contour lines from their correct positions 
at the several test sections. It is gratifying to see that such a simple computation yielas 
results which agree with the more elaborate tabulations. 
Table II is a similar comparison where the quantities now resemble ground dimen- 
sions. 
Table III conforms in general to the example of Lindig, mentioned below. 
The reader will have no difficulty analyzing the results, which agree in general 
with what many have believed for several years. The A-8 plotter seems to have given 
the best results with the A-7 and C-8 next. There is no apparent difference between 
the work of the C-8 and A-7 although the number of specimens was not sufficient to 
properly judge the performance of the C-8. The Kelsh plotter ranked next and the 
Balplex last.