6in dia brass & stainless steel station pointer.
Admiralty pattern 81. Hydrographic office , Royal Navy.
Serial number 7620/RML/218
The station pointer allows an observers location to be plotted on a chart by measuring with a sextant the relative angles of three known objects (e.g. land features) from the observers position and setting the moveable arms to the observed angles.
By placing the instrument on the chart and aligning the arms with the known objects, the centre of the circle indicates the observers position. The instruments principal uses, therefore, were for surveying or for fixing a ships position when near land.
49.5cm x 19.5cm x 6cm
Weight 6 kg