Basic differences among Prismatic Compass and Surveyors Compass

Compass belongs to an instrument that plays an important role to workout the direction of a survey line relative to magnetic north-south.

The magnetic north-south direction is treated as the reference direction and it is known as meridian (reference direction) and the angle among the line and the meridian is known as bearing. The compass is applied for calculating the direction of a line to simplify the surveying process significantly.

The variations among prismatic and surveyor’s compass are given below :-

Prismatic Compass

1. Graduation circle is attached to a broad type needle. Therefore, it will not revolve with the line of sight.
2. A prism is situated at viewing end.
3. Sighting and reading are performed concurrently.
4. The magnetic needle does not perform like an index.
5. The graduations are in whole circle bearing.
6. Graduations are pointed inverted as its reflection is examined via prism.
7. The reading is captured through a prism.
8. Tripod may or may not be applied. It can be persisted with a stretched hand also.

Surveyors Compass

1. Graduation circle is attached to the box. Si, it revolves with the line of sight.
2. No prism exists at viewing end except for a slit.
3. It is not possible to perform sighting and viewing all together.
4. Magnetic needle functions as index at the time of reading.

5. The graduations remain in quadrantal system.
6. Graduations are pointed directly. They are not inverted.
7. The reading is captured by directly viewing from top glass.

8. Tripod is necessary for being applied.

Basic differences among Prismatic Compass and Surveyors Compass