Obstacle in Chaining but not in Ranging:

Chaining and Ranging are two methods of surveying. While chaining involves measuring distances in a straight line, ranging is measuring distances between points that are not in a straight line. An obstacle in chaining is a feature that makes it difficult to measure distances in a straight line. Here, we will discuss why a river is an obstacle in chaining but not in ranging.

Why a river is an obstacle in chaining but not in ranging?

Chaining involves measuring distances in a straight line. If there is a river in the way, it is difficult to measure the distance across the river. This is because it is not possible to measure the distance in a straight line. Therefore, the river becomes an obstacle in chaining.

On the other hand, ranging involves measuring distances between points that are not in a straight line. In this case, the river is not an obstacle as the surveyor can measure the distance between the two points on either side of the river and then add the distance across the river. This method of ranging is known as offsetting.

Conclusion:

The river is an obstacle in chaining but not in ranging as ranging involves measuring distances between points that are not in a straight line. If there is a river in the way, the surveyor can use the offsetting method to measure the distance between the two points on either side of the river and then add the distance across the river.