72 
Roads are scribed with a double sapphire which is free 
to move in its swivel graver. 
The next step is the addition of the contours, which are 
scribed with rigid and swivel gravers, depending upon the 
nature of terrain. Fig. 3. 
The final step is scribing of the soil classification foil. 
The soil classification boundaries are stippled by means of 
the «Rotograph» and the symbols for the natural features 
are scribed with the aid of specially prepared templates. 
The illustrations show the most important tools used in 
the preparation of the reproduction materials up to the stage 
of black- and white copying and four-colour printing. 
Accuracy Requ irements. 
The map must be accurate within the following limits: 
A. Mean square error for reference points not more than 
+ 2.0 metres. 
B. Mean square error for altitude points not more than 
t 1.5 metres. 
C. Mean error contours not more than - (1.5—3tg a) 
metres. 
D. Where the terrain is exceptionally difficult (uneven, 
steep and heavily broken formation, covered by under- 
erouth, bushes etc.) an increase of the mean contour 
error of up to 50 % is permissible. 
E. Serious errors (three times the mean error) must not 
occur more frequently than once for every 50 points 
checked. 
Material to be Supplied: 
Normally, the following material is to be supplied to the 
province: 
1. Originals and material for reproduction. 
?. Diapositives and other photographic material which 
has been used in the cartographic work. 
3. Observation logs and calculations. 
4. Table of coordinates and altitudes of geodetic reference 
points. 
5. A short report on the work. 
The distribution of the economic map is normally under- 
taken by the province.