220 LE NATURALISTE CANADIEN 
Dr. E. Deville, Surveyor General ; and Dr. W. B. Daw- 
son, Superintendent of the Tidal and Current Survey. 
In the Union of Geodesy and Geophysics, the geophy- 
sical side is chiefly concerned, and occanography and the 
tides, and with meteorology. This presents some features 
of special interest, as it is only within quite recent years 
that any unity has been established in the tidal branch. In 
Canada, the one Superintendent has been in charge of the 
Survey Of Tides and Currents since 1894 ; and by being 
first in the field, he had the opportunity to organize the 
Survey on broader lines than in most countries, as well as 
to establish a basis for the work of other surveys which 
require tidal data to begin upon. The tides in their origin 
are undoubtedly due to the movements of the sun and 
moon and the astronomers claim them as coming under 
their supervision, and view them entirely from their stand- 
point. On the other hand, those more directly interested 
in mundane affairs, such as the navigator and the ship 
captain, consider the tides to be chiefly of interest to them- 
selves ; and they looked to the Hydrographer who makes 
charts for their benefit, to indicate what depth of water 
they could count upon, according as the tide should be 
high or low, and in what direction the tidal streams would 
carry their vessels. Again when extended levelling was 
inaugurated in any country, the surveyors required, first of 
all, the mean level of the sea as a datum to start from, and 
they found it necessary to take careful observations of the 
tide to arrive at a basis for their work. In some countries 
such as Holland, where large areas are below sea level, the 
effect of storms in raising the tide above its usual height 
was the matter of supreme interest. An appeal was, there- 
fore, made to the meteorologist to determine the extreme 
level during storms which the tide might reach, in order 
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