VII. l.c. Forest inventory in Dutch New Guinea 
At the request of the Dutch Government an area of 6500 sq. km situated in the north- 
west part of the country was type-mapped from aerial photographs. This work was executed 
by the I.T.C. Forestry Section in Delft (Netherlands). It was possible to complete the 
whole project in 4 months and the person in charge already had experience in the photo- 
interpretation of tropical forest. 
The photographic material used for this purpose was obtained by a Zeiss RMK p 10 
camera. Photographs were made on a scale of 1 : 40.000. The interpretation was carried 
out with the help of existing stereograms (keys), available literature and by general 
knowledge of vegetation in tropical countries. In this particular case the following vegeta- 
tion types could be identified on the photographs: dry land forests, fresh water swamp- 
and seasonal swamp forests, peat swamp forests, grass and reed swamps and swamp forests 
with a predominant occurrance of sago palm (Metroxylon sp.). Some of these vegetation 
types could be subdivided according to height and average crown size classes. In some 
cases individual tree species could be recognized on the photographs e.g. Agathis sp. 
The equipment used for this interpretation work was an ordinary pocket stereoscope, 
whereas for the delineation of types the normal mirror stereoscope is the most practical 
one. The annotated vegetation boundaries were afterwards transferred to available topo- 
graphic maps by Zeiss Sketchmaster. Mapping scale was 1 : 40.000. An occasional check 
made in the terrain afterwards showed that the vegetation boundaries mapped were in 
accordance with the situation in the field. 
VII. 2. Soil survey and photo-interpretation for agriculture 
For the soil survey of the Netherlands, aerial photographs are more or less continually 
used in those regions where the relief is sufficient to give good results in interpretation. 
Airphotos are also used as a field map in those regions where the existing topographical 
maps do not give sufficiently detailed information on the boundaries of fields and the 
situation of field roads. 
In Netherlands New Guinea the interpretation of aerial photographs has during the 
past four years extended along with the increasing activity of soil surveys for the develop- 
ment of this country. For this purpose, in one case, use could still be made of the oldest 
airphotos of this country, made by the B.P.M. in 1937. 
In Surinam, the interpretation of aerial photographs is a routine feature in the soil 
survey. The work in this country is demonstrated in two publications, by Van der Eijk 
and by Van der Voorde respectively, both published during the period reported. 
At the I. T.C. at Delft, there was during this period a marked increase of students from 
various countries who obtained basic instruction in the use of aerial photographs for soil 
survey, landclassification and soil- and waterconservation. More than 100 students, coming 
from 18 different countries received instruction in this subject. Apart from this, short 
courses were given to a large number of soil scientists. Various members of the I. T.C. 
Soils staff were engaged for large projects in foreign countries, either through F.A.O. or 
directly in the service of the respective governments. Of these special mention should be 
made of the work done in Iraq and Iran, and the projects still going on in Syria (U.A.R.), 
Columbia, the Union of South Africa and Egypt (U.A.R.). On various occasions, members 
of the I. T.C. Soils staff were cooperating with consultant firms or other private bodies 
for the carrying out of special surveys for development projects, for instance in Iran, Iraq, 
Nigeria, Tanganyika and the Union of South Africa. 
Soil surveyors from the Netherlands are also working in various other countries. They 
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