Closed contours with higher value inside represents a

The least count of a vernier scale is

For a line AB

Isogonics lines are the lines having the same

At magnetic poles, the dip of magnetic needle is

The size of plane table is

One mile equals to

The systematic errors which persist and have regular effects in the performance of a survey operation are due to

While doing levelling in undulating terrain, it is preferable to set the level on: