1.1 Remote Sensing Technique being Introduced 
In the first decades of the twentieth century the ice situation was 
still observed by visual reconnaissance, reported, however, by 
wireless telegraphy or telephony. Thus, a kind of remote sensing 
technique was .then introduced. 
In the early twenties the reconnoitered sea area was considerably 
widened by the use of airplanes and later of helicopters as well. 
At the same time photography was introduced for picturing the ice 
situation. The exposed film was then normally developed either 
aboard the ship or at a laboratory ashore. 
In the thirties radio navigation systems came into use, and the 
first radar systems were developed. The picture of the viewed area 
was continuously transmitted from plane or helicopter and received 
aboard the ship on a TV-screen. This was a great advance, indeed, 
and it offered the bridge officer a possibility to choose the most 
suitable route and to stand for cracks and lanes, etc., in the ice 
fields. 
2 PHOTOGRAPHIC INTERPRETATION OF ICE 
2.1 The IXth International Congress in London, 1960 
The report on "Photographic Interpretation of Ice" to the IXth 
International Congress in London, 1960, by the Chairman, Captain 
Ragnar Thorén, Royal Swedish Navy, Stockholm, included papers by 
Professor, Dr. Geza Teleki, Department of Geology, George Washington 
University, Washington, D.C., U.S.A., Dr. Terence Armstrong, Scott 
Polar Research Institute, Cambridge, England, Dr. Moira Dunbar, 
Directorate of Physical Research (Geophysics), Defence Research 
Board, Department of National Defence, Ottawa, Canada, and 
Professor, Dr. Erkki Palosuo, Institute of Marine Research, Helsinki 
(Helsingfors), Finland, all dealing with Ice at Sea, further a 
paper on "Glacier Inventory from Air Photographs", by Professor, 
Dr. Valter Sehytt, The Institute of Natural Geography, University 
of Stockholm, Sweden.