Theory
It is circular in shape and its diameter is 110 mm. It is made up of a non magnetic material. The different part of prismatic compass observed were.
- A magnetic needle supported over a pivot made upto hard steel.
- A graduated circle is attached with the needle. The graduation start from zero marked at south end of the needle and they run clockwise so that 90, 180, 270 where marked written are interval.
- Eye vane and object vane were fixed diametrically opposite to each other.
- Reflecting prism is provided near eye rang.
- Focusing stud is provided to adjust the eye sight or different persons.
- A base pin is provided to stop the inclination of the ring.
- Some glasses were provided to facilate the sighting or objecting in sunlight.
- Hinged mirror with object vane is provided to sight the objects which are to low or to high.
- The least count of line prismatic compass observed by 30 mm.
Diagram
Uses
It is mainly used to determine the bearing.
