(11) 
operation. The effective range depends on the flying height, H; the expression 
“Range=l -4 -y/h” gives a fair approximation of its value, where H is in feet and 
the range is in miles. These factors must all be considered when preparing the 
flight-line map. 
Experimental shoran-controlled photography has been conducted in the 
Ottawa area in winter months with excellent results and an effort was made in 
1951 to do some in the northern areas in conjunction with the line-crossings. Due 
to the limited number of ground sets with the necessity of movement immediately 
after line measurement, the amount of photography obtained was quite limited, 
although the weather conditions were average. In an operation as large as ours, 
it was not expected to produce quantity but only incidental photography, the main 
effort being directed to advance the shoran control as far as possible in the limited 
season. 
The amount of vertical and oblique photography of the northern areas avail 
able now for mapping purposes is enormous. Hitherto it has been used for small- 
scale mapping but the material is available for large-scale mapping as soon as 
more accurate control is established. Shoran has supplied this control in the areas 
so far covered. It is anticipated that a contract for shoran-controlled photography 
will be let in 1952 to fly an area of 172,000 square miles involving 14,000 lineal 
miles. Control flight lines over the existing vertical photography will be spaced 
at intervals of twenty minutes of latitude (23 miles) and one degree of longitude 
(30 miles). 
Conclusion 
A brief description such as outlined above may convey to the reader the 
extent to which electronics are clothing survey organizations in seven-league boots. 
Canada with its northern areas, over which the normal methods of control are 
slow and difficult, offers a wonderful field for the use of electronic methods. 
Doubts as to the accuracy possible in shoran have been removed by the results 
of application, and experience has indicated further lines of improvement. Shoran 
has been made to work to our purpose. 
As the frontier is being pushed back through air transportation, economic 
development is accelerated, mapping is to the fore, and the modern survey tool 
“Shoran” is making possible the realization of the dreams of geodesists and 
mappers, that of being ready with control data and maps previous to or con 
current with the other developments. We have always pressed for this effective 
result but not until recently has it been possible to achieve it. 
SOMMAIRE DES OPÉRATIONS POUR MESURER LA DISTANCE AU 
CANADA EN EMPLOYANT LE SYSTÈME ÉLECTRONIQUE 
SHORAN 
La mesure précise de la distance par la méthode de triangulation et de 
nivellement est, en général, surtout confinée aux régions bien établies du Canada 
qui longent les limites sud de ce pays d’une côte à l’autre. La triangulation 
s’étend le long de la côte du Pacifique jusqu’au territoire du Yukon et une branche 
isolée de triangulation secondaire court du Golfe Saint-Laurent jusqu’à la Baie 
Ungava du détroit d’Hudson. 
61667—2\