An instrument for taking azimuths and altitudes simultaneously
- an instrument that measures the height and azimuth of celestial systems; utilized in navigation
- An instrument when planning on taking azimuths and altitudes simultaneously.
(n.) An instrument when planning on taking azimuths and altitudes simultaneously.
In September 1839 a 3-foot speculum was finished and mounted on an altazimuth stand similar to Herschel's; but, though the definition of the images was good (except that the diffraction at the joints of the speculum caused minute rays in the case of a very bright star), and its peculiar skeleton form allowed the speculum to follow atmospheric changes of temperature very quickly, Lord Rosse decided to cast a solid 3-foot speculum.