nents of earlier 
undary through 
ada and Alaska. 
King, a former 
er. Other well- 
lle system were 
ie by the British 
stem in Canada 
H. Boyd where 
otographs have 
ces of a simple 
stem and these 
type camera is 
the standards of 
the telescope of 
lities of stereo- 
efore the Royal 
built a plotting 
se was made of 
although, quite 
r were acquired 
CANADA 
nent committee 
f Parliament to 
e first record of 
rveyor General's 
ircraft might be 
on, an engineer, 
onsulted Deville 
ot display much 
rveyor General 
ig were made in 
ose of Professor 
ried out in the 
tifying and pro- 
fully contoured 
vide-angle plate 
| fairly complete 
und in Ref. 3. 
(5) 
Meanwhile, the Air Board was obtaining photographs in the course of 
forestry patrols, transport and other activities. Wilson therefore requested 
Deville to assign a surveyor for devising a systematic index for these photographs 
and for investigating their possibilities in mapping. This was done, and plotting 
experiments were commenced under the supervision of R. B. McKay, who did 
so much to apply photogrammetry to Canadian requirements and conditions. 
. The first experiments in the Surveyor General's office utilized a few oblique 
views taken along a route where some ground control existed and relief was 
negligible. The plotting methods tried were entirely graphical and were based 
on the control visible in the photograph. This control was made to form the 
basis for grids permitting the ready transfer from photograph to plot of detail 
in the intricate system of water features shown. In this way, the traverse was 
extended a considerable distance beyond the shores or islands visible to a survevor 
from water level. The results were considered encouraging in that, as compared 
with ground surveys, much more information appeared on the map, but the 
methods were found rather slow. 
The clarity of the image of the apparent horizon shown on some of these 
oblique views, taken in the course of an inspection flight in 1922 by A. M. Narra- 
way, then Controller of Surveys, suggested to Deville a more direct way of 
gridding the photographs. In this the lines of the grid were made to conform 
to the cardinal directions, as deduced from the azimuth of the control traverse 
course, with a spacing in agreement with the plotting scale (Ref. 3). This 
method required a knowledge of the principal distance, and the location of the 
principal point, and hence needed camera calibration. 
At about this time also, Deville proposed the use of a four-lens camera for 
photographing from horizon to horizon in a manner similar to the present-day 
tri-metrogon arrangement. But quotations submitted for the mechanical design 
and construction were prohibitive with the funds available, and the proposal 
was shelved (Ref. 3). 
In 1923 air activities were expanded under the direction of the Department 
of National Defence, which had taken over the functions of the Air Board as 
from 1 January, 1923. The encouraging results so far obtained in mapping 
gave rise to an increase in photographic flights for this purpose, and it was 
arranged that a surveyor accompany each photographic aircraft as a guide and 
navigator. The first three surveyors to be thus employed were J. Carroll, 
R. D. Davidson and E. S. Fry, and all these have made valuable contributions 
to Canadian mapping problems. 
It was soon realized that Deville's method of gridding each photograph was 
too slow for quantity production and McKay introduced the procedure, soon 
known as the Canadian" method, depending on stock projection grids having 
lines parallel and perpendicular to the horizon at fixed ground spacing (Ref. 19). 
The technique of plotting from oblique photographs was also developed by M. G. 
Cameron, who introduced the system of employing long “azimuth” lines to 
control direction through a strip. 
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