Sweden 13 
the accuracy to the scale of the negatives. See Moller [14] and [82 j. 
The expenses and the different work moments have been studied in a 
number of geodetic and photogrammetric maps for town and country 
planning on a scale of 1:2 000. See |35]. The combination of geodetic 
and photogrammetric mapping methods, particularly to scales of 
1:4 000 and 1:8 000, has also been studied and tested in practice. See 
[83]. 
The Photo Section of the General Staff has examined a new mecha 
nical radial triangulation equipment, the principles of which were de 
veloped by Fagerholm, [5] and [50]. 
C. Institutions mainly using Air Photogrammetric Pictures and 
Maps for Technical and Military Purposes 
The State Power Board 
The Purposes and Extent of its Photogrammetric Activities. The 
State Power Board uses medium and large scale maps for its project 
ing, planning and constructing activities as well as for assessment of 
damages. These activities are firstly concentrated to such parts of North 
Sweden, where large or medium scale maps are seldom available. There 
fore the Board has had to produce such maps for its own use exten 
sively. 
Earlier all the maps of the Board were produced by geodetic methods, 
but since some years photogrammetric methods are increasingly used, 
and now the main part of the mapping is done photogrammetrically. 
By 1947 the State Power Board had already had most of the large 
rivers in North Sweden photographed from the air and these photo 
graphs have since been used for many different purposes. In the last 
few years photographs have been extensively taken for special purposes 
from both high and low heights. One example of this is the geodetic- 
photogrammetric mapping of the Skellefte River. This was begun in 
the summer of 1954 in close collaboration with the Geographical Survey 
Office, and in that work Geodimeter traverses were for the first time 
used in Sweden to support photogrammetric triangulation. 
In 1955 1180 photographs were taken on a scale of 1:36 000, and 
1850 photographs on larger scales of up to 1:4 000. The small scale 
photos cover important districts containing the lakes from which many 
of the large Norrland rivers spring. All this material will in the en 
suing years be adapted to some extent by photo-interpretation, but to 
an even greater extent by photogrammetric triangulation and plotting. 
In producing maps necessary for projecting, planning and construc 
tion of hydro-electric power-plants the Board has more and more gone 
over from the traditional geodetic to photogrammetric plotting methods. 
In 1955 line maps with contours have been produced photogrammetri 
cally to the following extent: