Difference between Prismatic Compass and Surveyor Compass

Difference between Prismatic Compass and Surveyor Compass

Prismatic Compass and Surveyor's Compass are two different types of compasses used in surveying for measuring angles and bearings. They have distinct characteristics and applications:

1. Prismatic Compass:

   • Design: The prismatic compass is a simple and compact compass with a prism attached to it.
   • Use: It is primarily used for measuring magnetic bearings (angles relative to magnetic north) and is well-suited for reconnaissance surveys, preliminary surveys, and rough traversing.
   • Accuracy: Prismatic compasses are generally less accurate compared to surveyor's compasses and are suitable for less precise work.
   • Features: Prismatic compasses often have a sighting mechanism with a peephole and a hairline to aim at the target.
   • Portability: They are lightweight and easy to carry, making them suitable for fieldwork.

 

1. Surveyor's Compass (or Transit Compass):

   • Design: Surveyor's compasses are more sophisticated and precise instruments. They consist of a magnetic compass needle and an alidade (a sighting device) mounted on a graduated circle.
   • Use: They are used for measuring both magnetic bearings and angles in relation to true north. Surveyor's compasses are essential for more accurate land surveys, boundary marking, and topographic mapping.
   • Accuracy: These compasses are designed for high accuracy and can provide precise angle measurements.
   • Features: Surveyor's compasses often include additional features like vernier scales for more accurate readings, bubble levels for leveling the instrument, and sometimes telescopic sights for precise targeting.
   • Portability: While surveyor's compasses are bulkier and heavier than prismatic compasses, they are still portable enough for most field surveying tasks.

 

In summary, prismatic compasses are simpler, lightweight instruments suitable for less precise work and quick measurements, while surveyor's compasses are more complex and accurate instruments used for detailed land surveys and mapping tasks. The choice between them depends on the specific requirements and accuracy needed for a given surveying project.