- a telescope mounted to point only at the zenith, used at some observatories for measuring time by the stars.
Origin of zenith tube
First recorded in 1830–40
Also called zenith telescope.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- an instrument used to determine the latitude of stars, similar to the meridian circle but fitted with an extremely sensitive level and a declination micrometer
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012