47) Which levelling is only the back sight and fore sight readings are taken at every set up of the level and no distance are measured along the direction of levelling?

48) What is the name of level, if the fly levelling done at the end of day's work to connect the finishing point with the starting point on that particular day?

49) Which method gives approximate result and so it is adopted in the reconnaissance or in the preliminary survey?

50) What is the name of the levelling while the relative elevations of different points are obtained by measuring the vertical angles and horizontal distance?

51) What level is required for permanent adjustment if the bubble axis made parallel to collimation axis of the telescope?