বাংলাদেশ জরিপ অধিদপ্তর মেনু নির্বাচন করুন Ramsden's theodolite represented a terrific phase ahead from the instrument's accuracy. William Gascoigne invented an instrument that utilised a telescope having an set up crosshair for a concentrate on system, in 1640. James Watt designed an optical meter with the measuring of length https://amird085ucj1.wikibyby.com/user