Source : Webster's Revised Unabridged Dictionary (1913)

Inclinnometer \In`clin*nom"e*ter\, n. [Incline + -meter.]
   (Magnetism)
   An apparatus to determine the inclination of the earth's
   magnetic force to the plane of the horizon; -- called also
   {inclination compass}, and {dip circle}.

Source : WordNet®

dip circle
     n : a measuring instrument for measuring the angle of magnetic
         dip (as from an airplane) [syn: {inclinometer}]