The instrument which enables a surveyor to find the direction of a base line is
Answer Details
The instrument which enables a surveyor to find the direction of a base line is the magnetic compass. A magnetic compass is a tool that uses the Earth's magnetic field to determine the direction of North, South, East, and West. The surveyor would use the magnetic compass to align the base line in the direction he or she desires before taking measurements. The other options, such as the abney level, ranging pole, and plumb bob, are surveying tools, but they are not used specifically for determining the direction of a base line.