Explain temporary adjustment of plane table survey.
1 Answer
1. Setting over the station: The plane table is fixed on tripod and adjust the table in such a way that table is approximately level.
2. Leveling the table: The tubular or spirit level is placed in two perpendicular directions and tripod legs are adjusted to bring the bubble in center.
3. Centering the table: Place the plumb bob with upper leg of U-fork on sheet and its pointed end over the station mark. If it is not over the station mark, adjust the legs of tripod to bring plumb bob exactly over the station mark.
4. Orientating the plane table: It is to be carried out if table is to be set up at more than one station.
The table can be oriented in two ways.
i. Using trough compass.
ii. By back sighting.
2. Leveling the table: The tubular or spirit level is placed in two perpendicular directions and tripod legs are adjusted to bring the bubble in center.
3. Centering the table: Place the plumb bob with upper leg of U-fork on sheet and its pointed end over the station mark. If it is not over the station mark, adjust the legs of tripod to bring plumb bob exactly over the station mark.
4. Orientating the plane table: It is to be carried out if table is to be set up at more than one station.
The table can be oriented in two ways.
i. Using trough compass.
ii. By back sighting.