The undertakings of Mr. Henry Bond Senior, a famous teacher of the art of navigation in London, concerning the variation of the variation of the magnetical compass and the inclination of the inclinatory needle; as the result and conclusion of 38. Years magnetical study

Abstract

The said Mr. Bond can shew the Cause of the Variation of the Variation of the Magnetical Needle or Compass by the Motion of two Magnetical Poles ; how these Poles are found; and what their Distance is from the Poles of the Earth; what their Annual Motion is, and from whence it proceeds.