In the beginning, when man made boats, he also used them for the sea voyages. But he did not dare to travel too far because of the fear of losing his way as he did not have any instrument to find directions in the sea. During those days, sea travellers used to find different directions with the help of the Sun and the stars. But when the Sun and the stars were not visible in a cloudy weather, finding the right direction was very difficult. About 1000 B.C., a black stone with peculiar properties was discovered at Magnesia in Asia Minor. It used to attract small iron pieces. This stone was named as ‘magnet’ since it was discovered in Magnesia. It was observed that a freely suspended magnet always points towards the north and south. It is because the Earth itself behaves as a huge magnet and as such attracts the poles of the magnet. The Chinese navigators utilised this in the sea. This is how the first ‘compass’ of the world was made. In the primitive compasses a cork or a piece of wood used to be floated in a water bowl and a piece of the magnetic stone was placed on it. The modern compasses consist of a small non-metallic box with a thick paper dial covered with a glass plate. The paper is divided into four right angles, each angle representing one direction. They are denoted by N, S, E and W for North, South, East and West. Each quarter of the circle is further divided into eight equal parts. In this way, the whole circle is divided into 32 parts. In the centre of this circle, a magnetic needle is pivoted which freely rotates in horizontal direction. The magnet pointing in the north-south direction helps the navigators to determine the direction in which the ship is sailing. In many ships nowadays, another kind of instrument named ‘gyrocompass’ is also used. In fact, ‘gyrocompass’ is a continuously driven instrument which acts as a compass. It is unaffected by magnetic variations and is used for steering ships as well.
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