(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.

• Main Authors: Canada. Department of Mines and Technical Surveys, Nicholson, N. L. (Norman Leon), Comtois, Paul
• Format: Text
• Language: unknown
• Published: Department of Mines and Technical Surveys, Geographical Branch 1957
• Subjects: Earthquake; Geomagnetism; Canada; Nicholson; North Pole; Newfoundland; North Magnetic Pole
• 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

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...