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SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
major emphasis placed on observing sea ice conditions in the former. The 
second phase was extended over a three-week period through use of the 
Magnetic Attitude Control mechanism, an electric circuit, actuated on com 
mand from the ground, which produces a magnetic coupling with the earth’s 
field to speed or to retard the normal spin precession. 
Fig. 1 is a mosaic of aircraft pictures taken by a Canadian aircraft at 
40,000 feet on April 7, during Phase II of Project tirec. The north coast of 
Prince Edward Island can be seen near the bottom of the picture, and the 
Magdalen Islands in the upper right. Fast ice outlines the Prince Edward 
Island coast; open water separates this fast ice from the heavy ice concentra 
tion north of the island. 
Fig. 1. 
While the overall ice concentration in this area is approximately eight-tenths, 
the size of individual ice elements varies considerably, ranging from brash and 
block ice to giant floes and fields. One of the largest fields seen here is roughly 
17 miles long and 8 miles wide. The area immediately west and north of the 
Magdalen Islands shows an ice “peninsula” extending northeast from the 
main ice pack. Individual floes can be seen along a line through the center 
of this “peninsula”, where the concentration is less than 10/10, creating a 
light grey appearance in contrast to the brighter surrounding ice of 10/10 
concentration.