4 
about 30 feet. In addition to this main net, a second-order 
accuracy triangulation net had been extended from Bay of Islands 
across the railroad belt to the city of St. John's on the east coast, 
and some precise levels had been established along the main rail- 
road. 
The task that confronted the Federal Government mapping 
agencies was indeed formidable - virtually the mapping of the 
whole Island of Newfoundland. Tiam ing the air photography and 
planning and carrying out field surve oys and map compilation were 
the responsibility of the Topographical Survey of the Department 
of Mines and Technical Surveys assisted by the Army Survey 
Establishment of the Department of National Defence. Arrange- 
ments were made through the Interdepartmental Committee on 
Air Surveys for the progressive completion of air photography to 
specifications prepared by the National Research Council. 
Cameras equipped with six-inch wide-angle cones were used for 
all photography and the most common scale specified was 
1:40, 000. 
At this time, the Topographical Survey was making radical 
  
changes in its field and office techniques. The urgency of the 
mapping project, together with the fact that the large island area 
  
seemed well suited to the employment of high-production methods, 
gave additional impetus to the changes. In the field, considerable 
use was to be made of helicopters for transporting surveyors, 
and in the office 1 he multiplex method of extending control and 
plotting detail was displacing the time-worn method of reading 
parallax and sketching contours on photo prints. 
  
Field operations were commenced in 1949 on the Avalon 
Peninsula and along the east coast where 1:40, 000 photography 
was available and Geodetic Survey control was readily accessible. 
Since most of the hill tops were bare, horizont al control was 
generally extended by triangulation and vertical control by verti- 
cal angulation supplemented by stadia and barometric levelling. 
As the work moved away from geodetic control, additional tri- 
angulation nets were established although to lower standards of 
accuracy than the geodetic nets. From 1949 to 1954, ground 
survey parties continued work along the east and south coast, 
some of the engineers in charge of these parties having had pre- 
vious service on similar work for the Newfoundland Government,