| 单词 | position micrometer | 
| 释义 | > as lemmasposition micrometer   position micrometer  n. now rare an apparatus for measuring the position angle of one celestial object relative to another, containing a thread or wire mounted at the common focus of the objective lens and eyepiece of a telescope, which can be rotated in a plane perpendicular to the axis of the telescope; an apparatus similarly used with a microscope. ΚΠ 1839    Penny Cycl. XV. 175/2  				We should recommend fixing the position micrometer upon a slipping-piece. 1871    tr.  H. Frey Microscope & Microsc. Technol. 655 		(advt.)	  				The whole stage rotates concentrically and independently by means of a rack and pinion on a circular plate, graduated so as to form a goniometer or position micrometer. 1997    I. Ridpath Dict. Astron. 166  				Many filar micrometers can also be rotated against an angular scale; such a device is known as a position micrometer. < as lemmas | 
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