error due to horizontal axis not being perpendicular to the vertical axis

index error i.e. error due to imperfect adjustment of the vertical circle vernier

error due to non-parallelism of the axis of telescope level and line of collimation

none of the above

increase

decrease

not change

either 'a' or 'b'

only (i)

both (i) and (iv)

only (iii)

both (ii) and (iii)

horizontal line

line parallel to the mean spheriodal surface of earth

line passing through the center of cross hairs and the center of eye piece

line passing through the objective lens and the eye-piece of a dumpy or tilting level

foresight only

backsight only

foresight and backsight

foresight and intermediate sight