*Ranging a line: The operation of establishing intermediate ranging rods in line with the end ranging rod of line is called ranging a line.It is done prior to chaining a line to establish a straight path between it's end stations.
Ranging is generally done by judgement of eye or by line ranger but in important survey with a theodolite is used.
The ranging rods fixed at the end of a ranging line may or may not be interviewing.the ranging can be done directly but when they are not intervisible due to intervening height ground etc indirect method has to be adopted there.
Ranging is done by judgement of eye and also by a line ranger.
The surveyor Stands about 2m behind the ranging rod at the standing point of the line while the assistant hold the ranging rod at arm's length near the point where it is desired to fix the intermediate station.the surveyor them looking to the end ranging rod directs the assistant by using Hand signals,to move right or left until the three ranging rods appear to be exactly in straight line.
During measurements three types of errors occur namely natural error, personal error and instrumental error which define themselves by their literal meanings.