The surface if zero elevation around the earth, which is slightly irregular and curved, is known as ............

The ratio of the focal length of the objective to that of an eye-piece of a telescope is called its ............

Cross hairs in surveying telescope, are fitted ............

In case of double line river, contours are ............

If vertical angles of inclined sights do not exceed 10° and non-verticality of the staff remain within 1° stadia system …

The operation of revolving a plane table about its vertical axis so that all lines on the sheet become parallel to corre…

The longitudinal section of the surface of bubble tube is ............

The approximate formula for radial or perpendicular offsets from the tangent, is ............

The obstacle, which obstructs vision but not chaining is a ............