annular

[Fr. annulaire from Lat. annular is or anularis = pertaining to a signet ring; annulus or anulus a ring.] In the form of a ring ringed; wearing a ring, as annular finger. ( Beaumont: Psyche, 50.) 1. Min. An annular crystal is a hexagonal prism with six, or an octagonal prism with eight, marginal faces disposed in a ring about its base, or one or other of these prisms truncated on all its terminal edges. 2. Astron. An annular eclipse of the sun is an eclipse in which the whole of the moon is seen upon the sun's disc. The moon, however, in certain positions being too small to cover the disc, the sun appears in a form more or le resembling a ring. At other times the moon is so situated as to be able to produce a total eclipse of the greater luminary. (Herschel: ANNULLAR ECLIPSE. Astron., 5th ed., 1858, § 425.) An annular nebula is a nebula of a form suggestive of a ring. Such nebula exist, but are among the rarest objects in the heavens. A nebula of this character, situated between the stars β and y Lyræ, has been resolved by Lord Ro e's powerful telescope into a multitude of minute stars, with filaments of stars adhering to the edges. ( Ibid ., 10th ed., § 875.) 3. Anat.: Noting any part of the human frame which approaches the form of a ring. 226 "That they might not in bending the arm or leg rise up, he has tied them to the bones by annular ligaments, "-Cheyne. Annular protuberance: The same as the Pons Varolii . It is called also the Isthmus encephali, and the Nodus encephali. (Todd & Bowman: Physiol. Anat ., vol. i., pp. 273, 274.) 4. Arch . Annular vault : A vaulted roof supported on circular walls. ăn'-nū-lar-lý, adv. [Eng. annular; -ly.] In the form of a ring.