A telescope whose mounting has only two axes of motion, one parallel to the Earth's axis and the other one at right angles to it WordNet 3.0 & Open English WordNet

A kind of telescope mounted so as to have two axes of motion at right angles to each other, one of them parallel to the axis of the Earth, and each carrying a graduated circle, one for measuring declination, and the other right ascension, or the hour angle, so that the telescope may be directed, even in the daytime, to any star or other object whose right ascension and declination are known. Wiktionary

Kind of telescope. Wiktionary (translation)