Terms of Service 7. (x) Set the vernier A to a reading other than 0°, say, 60° or 90°). (ii) Set the vernier A to the zero or 360° of the horizontal circle so do this, loosen the upper clamp and tum the upper plate until the zero of vernier A nearly coincides with the zero of the horizontal circle. (xiii) The mean of the two results for each angle is taken as its true value. Lovingly crafted and maintained by. Visit our privacy To measure the horizontal angle AOB by repetition: (i) Set up the theodolite at station -point O and level it accurately. Reiteration Method. Horizontal Angles, Measurement of Horizontal Angles, Surveying, Theodolite Surveying. Check the reading at vernier A which should still be 0 or 360° and note the reading at vernier B. help you have the best experience while on the site. Tighten the lower clamp and bisect A exactly by turning the lower tangent screw. (xii) Close the horizon and apply the necessary correction to all the angles as before. this website. 3. It is generally preferred when several angles are to be measured at a particular station. Horizon closure Usually more angles are taken from one setup. Turn the instrument and direct the telescope approximately to the left hand object (A) by sighting over the top of the telescope. Privacy Policy 9. data. Check the vernier readings which must be the same as before. (vii) The vernier A should now read 360°. (viii) The mean of the two values of the angle AOB, one with the face left and the other with the face right, gives the required angle free from all instrumental errors. Closing the horizon is good for spur points, to show that a mistake wasn't made. Image Guidelines 4. The number of repetitions made usually is six, three with the face left and three with the face right. Design, CMS, Hosting & Web Development :: ePublishing, This website requires certain cookies to work and uses other cookies to help you have the best experience. The final reading of the vernier A should be the same as its initial reading. If large, the readings should be discarded and a new set of readings be taken. The mean of the two vernier readings gives the second value of the angle ABC which should be approximately or exactly equal to the previous value. Doubling angles on a traverse takes insignificantly more time than just turning single angles, and it's definitely worth doing. By visiting [gravityform id="1" title="false" description="false" ajax="true"]. Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. (i) Set up the theodolite at station-point O and level it accurately. Uploader Agreement. (iv) Loosen the upper clamp, turn the telescope clock-wise and bisect the right hand object (B) exactly by using the upper clamp and its tangent screw.