tellurion

1. (astronomy, historical) An instrument used to show how the rotation of the Earth on its axis and its orbit around the Sun cause day and night and the seasons.Examples: "The Second Part of this Orrery I call a Tellurian, [...] becauſe it ſhews moſt accurately and evidently all the Phœnomena ariſing from the Annual and Diurnal Motions of the Earth, in a Terreſtrial Globe full Three Inches in a Diameter; upon which all the Parts of the terraqueous Surface are diſtinctly delineated, [...]"; "Among the modern inventions appertaining to astronomy, besides the instruments necessary to correct observation, we may reckon those curious and elegant machines, exhibiting the motions and phenomena of our solar system and its several parts; our orreries, planetariums, tellurians, lunariums, &c., all of which may be considered as extremely interesting and ingenious contrivances."historical