17) Which compass sighting and reading cannot be done simultaneously from one position of the observer?

18) Which compass the reading is taken with the help of a prism provided with the eye view?

19) Which compass can either be used as a hand instrument or can be fitted on a tripod?

20) Which compass graduated ring is attached with the needle?

21) What is the name of quadrant, if a line lies in between 90 Degree and 180 Degree?