zenith sector การใช้

• Balta was the northernmost station of the zenith sector.
• He worked at Greenwich observatory with Ramsden's zenith sector and in 1837 he was engineer in charge of Woolwich Dockyard.
• A classic zenith telescope, also known as a "'zenith sector "'employs a strong altazimuth mount, fitted with levelling screws.
• Graham made for Edmond Halley the great mural quadrant at Greenwich Observatory, and also the fine transit instrument and the zenith sector used by James Bradley in his discoveries.
• His collimator was meant to replace a level, or plumb-line, in astronomical observations, and to furnish a ready and perfectly exact method of determining the position of the horizontal or zenith point on the limb of a circle or zenith sector.