In ancient times if a country was attacked by the king of another country, then in order to gauge his army’s movements, ears were pressed to the ground so as to find out from which direction and from what distance these movements are taking place. Regarding sound it is said that it is heard via the medium of wind but the reality is that the grasping and broadcasting power of earth is much more than that of wind.
Ordinarily in order to hear sounds ears are made use of. Yet the prowess and capacity of ears are limited. One of the reasons being that sound is not of only one type. The vibrations of some sound are such that by banging against our ear drums create upheavals that can be experienced by our ears. Those that are of this stature only can be heard by the ears. The 2nd reason is that despite them being capable of being ‘caught’ by the ears, they become so light and very thin due to a very far off distance that the hears fail to hear these sounds. From many standpoints it is most required that we hear these sounds that are beyond the hearing capacity of the ears. Its utility lies in creative tasks and staving off calamities.
The far off movements of clouds can be heard by the ears of peacocks and it manifests this premonition via its voice emitting a lot of joy. Spiders possess premonitions about rain and on this basis it creates or swallows the mesh that it creates. Before a building gets razed to the ground, the cat’s ear hears it easily and before a wall or roof collapses, the cat hastily runs away from that place with her babies. Humans have fulfilled this requirement via the medium of scientific apparatus of sound sensitive technology and machines.
In this direction the 1st step of scientific progress was marching ahead on this belief that in comparison to wind, the sound grasping power of earth is much more. In the 2nd world war in order to gauge movements of the enemy army such a machine was designed which was buried under the ground a bit and the remaining part stood on the surface of the ground. It had a cavity of mica in which mercury was filled. From it 2 tubes emerged from it and these were placed in the ear opening. Just as in order to gauge heart beats we place a stethoscope on the chest to find out the inner body condition, in the same way this machine would give information regarding movements taking place on the ground that was at a far off distance.
Later technology that gauged vibrations and electrical energy in space came into vogue. In it was one machine that caught movements of space. Very easily in it one could hear the cannon movements of enemy army. When rifles or cannons are fired, 3 types of sound are heard. The 1st takes place when gas comes out of the hollow tube like passage. The 2nd takes place when the bullet whizzes ahead. The 3rd when the bullet actually hits the target. All these 3 types cannot be heard separately by our ears. This is because these movements take place so speedily that our ears and brain cannot separate them. Yet these machines can classify these 3 sounds quite deftly and one knows that how many bullets have been fired, at what distances and of what stature. tv installation