A compass is equipment which is used to find direction while at sea.
A compass tells the direction in which the ship is going or the direction of any other object.
An azimuth mirror is used in conjunction with a compass.
This device enables the operator to measure bearings of celestial and terrestrial objects.
Purpose of Azimuth mirrors (Azimuth Circle)
Azimuth mirror is used for taking the bearings of terrestrial and celestial objects.
By the use of mirrors or lenses or prisms or combination of all these, the equipment allows both, the readings of the compass card, and the object to be seen at the same time and in the same direction.
Thus the bearing of the object can be read out.
Azimuth mirror is therefore portable equipment which is placed over a magnetic or gyro compass for measuring bearings of terrestrial and celestial objects.
Sight Vanes (Near vane & far vane)
Allow the observer to take bearings of objects by aligning the two vanes to the object.
The near vane contains a peep sight while the far vane contains a vertical wire.
The far vane is mounted on top of a housing that contains a reflective mirror inside enabling the observer to read the bearing from the reflected portion of the compass card.
Reflector vane
Allow the observer to observe azimuths of celestial bodies (stars and planets) at various altitudes by picking up their reflection in the black mirror. When the body is observed, its reflection appears behind the vertical wire in the far vane.
Levels
Indicate if the ring is level with the horizon.
NOTE: Bearings read when the ring is not level are inaccurate.
Concave mirror
Reflects the sun’s rays onto the prism housing on the other side of the ring when the observer is taking an azimuth of the sun.
Prism Housing
Directs the beam of light from the concave mirror downward in a narrow beam onto the compass card enabling the observer to read the azimuth to the sun.