বাংলাদেশ জরিপ অধিদপ্তর মেনু নির্বাচন করুন Ramsden's theodolite represented a great step forward in the instrument's accuracy. William Gascoigne invented an instrument that utilized a telescope using an set up crosshair being a target unit, in 1640. James Watt made an optical meter for your measuring of distance in https://surveying-and-mapping-ban81468.blogmazing.com/28993327/not-known-details-about-land-survey-experts-bd