What type of compass is a prismatic compass?

A prismatic compass is characterized by its design, which includes a glass-topped case and a rotating needle. This type of compass provides a clear and direct reading of the bearing due to its unique optical system. The prism allows the user to read the compass bearing while simultaneously aligning the compass with the target, which enhances accuracy and usability in the field.

The prismatic compass integrates a mirror and a prism that enable the user to view the scale and the needle at the same time, ensuring that the compass can be used effectively in various lighting conditions. This tool is particularly useful in surveying and navigation where precision is crucial.

The other options refer to different instruments or tools that do not align with the specific features and functionality of a prismatic compass. While there are compasses designed for underwater navigation, they do not incorporate a prism arrangement. Similarly, devices for measuring area or calculating land slopes serve entirely different purposes and functions in the field of engineering and surveying.