2. For orientation of a plane table with three points A, B and C, Bessel's drill is
Options
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.
3. Diurnal variation of magnetic declination is
Options
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.