Abstract 
Water Current Measurement by Tidal Cycle Photography 
by 
H. L. Cameron 
Director, Photogrammetry and Geology Division 
Nova Scotia Research Foundation 
Strong tidal currents in Petit Passage and 
Grand Passage near the entrance to the Bay of Fundy, Nova 
Scotia, make pier and other harbour construction difficult 
to plan and maintain. As an aid to engineering planning, 
the two passages were photographed every fifteen minutes 
throughout a tidal cycle. That is, from high to low tide, 
and from low to high tide, 86 strips in all being taken. 
This photography was carried out by the RCAF at the 
request of the Dominion Public Works Department of Canada. 
The method of current measurement by anomalous parallax 
was used to plot the position of current maxima and their 
velocities. Forty six maps of Petit Passage have been 
prepared and, taken in groups on a light table, show the 
swing of the current from side to side and the variations 
in speed as the tidal cycle goes on. Counter currents and 
eddies were mapped and much interesting data obtained of 
value to both engineers and fishermen. The value of the 
Synoptic picture of the current is amply demonstrated. 
The Hydrographic Survey Division of the 
Topographic Survey of Canada ran a rigid test of this 
method on the Rideau Eve» using current meters to check 
the photogrammetric measurements. The test was so 
successful that they plan to adopt the method for coastal 
and arctic work, 
Further experiments are prorosed to test this 
technique by ultra high altitude small scale photography 
of tidal waves in large basins, and ocean currents such 
as the Gulf Stream.