Meaning of dialling sphere in English:

dialling sphere

noun

(US dialing sphere)
historical
  • A sphere with a horizon and two encircling, movable graduated circles, for use in designing or demonstrating a sundial.

    The two circles are fixed at right angles to each other to represent the meridian and the equator respectively. The instrument could also be used to demonstrate spherical triangles.

Origin

Early 18th century.