What is "astral lamp"

Astral \As"tral\, a. [L. astralis, fr. astrum star, Gr. ?: cf. F. astral. See Star.]

1. Pertaining to, coming from, or resembling, the stars; starry; starlike.

   Shines only with an astral luster.
   --I. Taylor.

   Some astral forms I must invoke by prayer.
   --Dryden.

2. (Biol.) Of or pertaining to an aster; as, astral rays; astral sphere.

3. (Theosophy) Consisting of, belonging to, or designating, a kind of supersensible substance alleged to be next above the tangible world in refinement; as, astral spirits; astral bodies of persons; astral current; the astral plane.

   Astral lamp, an Argand lamp so constructed that no shadow is cast upon the table by the flattened ring-shaped reservoir in which the oil is contained.

   Astral spirits, spirits formerly supposed to live in the heavenly bodies or the a["e]rial regions, and represented in the Middle Ages as fallen angels, spirits of the dead, or spirits originating in fire.

n. An Argand lamp constructed so that no shadow is cast upon the table by the flattened ring-shaped oil reservoir.