For orientation of a plane table with three points A, B and C, Bessel's drill is
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A. Align b through a and draw a ray towards c, align a through b and draw a ray towards c, finally align c through the point of intersection of the previously drawn rays
B. Align c through a and draw a ray towards b, align a through c and draw a ray towards b, finally align b through the point of intersection of the previously drawn rays
C. Align c through b and draw a ray towards a, align b through c and draw a ray towards a, finally align a, through the point of intersection of the previously, drawn rays
D. In the first two steps any two of the points may be used and a ray drawn towards the third point, which is sighted through the point of intersection of previously drawn rays in the final step.
Correct Answer
In the first two steps any two of the points may be used and a ray drawn towards the third point, which is sighted through the point of intersection of previously drawn rays in the final step.
Surveying problems
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1. Diurnal variation of magnetic declination is
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A. greater at equator than nearer the poles
B. less at equator than nearer the poles
C. less in summer than in winter
D. same at all latitudes and during different months.