(Text Page to) (18) Earthquakes, magnetism and tides : Lines of equal magnetic variation (isogones) -- Lines of equal annual change in magnetic variation (isopores) -- Semi-diurnal co-tidal and co-range lines west coast -- Semi-diurnal co-tidal and co-range lines east coast. Compiled from information supplied by the Dominion Observatories and Canadian Hydrographic Service. (Canada) Department of Mines and Technical Surveys.
Descriptive text on verso of (18) Earthquakes, magnetism and tides: Since the North Magnetic Pole is in a different position from the Geographical North Pole, and since the lines of the earth's magnetic forces are deflected by various agencies, the compass needle does not point toward the Geogr...
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Department of Mines and Technical Surveys, Geographical Branch
1957
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Online Access: | https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~323179~90092274 https://media.davidrumsey.com/MediaManager/srvr?mediafile=/Size4/RUMSEY~8~1/185/14001041.jpg |