| 单词 | refraction circle |
| 释义 | > as lemmasrefraction circle refraction circle n. Astronomy †(a) the setting circle of a refracting telescope (obsolete); (b) = transit circle n. at transit n. Compounds 2 (now historical and rare). ΘΚΠ the world > physical sensation > sight and vision > optical instruments > instrument for distant vision > [noun] > telescope > refracting telescopes > parts of refraction circle1788 1788 G. S. Howard New Royal Cycl. II. 835/1 The refraction circle is set to the same minute, &c. which the index points to on the limb of the quadrant. 1809 W. Nicholson Brit. Encycl. V. at Observatory A very small circle, called the refraction circle H, moveable by a finger screw at the extremity of the eye-end of the telescope. 1846 Sci. Amer. 26 June 317/2 The great Refraction Circle, ordered for the National Observatory, has arrived. 2003 S. J. Dick Sky & Ocean Joined vi. 211 (caption) The remaining portion..housed the 6.6-inch Ertel transit circle known as the ‘Refraction Circle’. < as lemmas |
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