Naturalist ancient Rome Pliny transmits common in his time the story of magnetic rock somewhere in India, near the sea, which powerfully attracted all sorts of metal objects. Woe to the sailor who had dared to approach his ship to this rock. It will pull from a vessel all nails, screws, metal braces, and the ship will break up into separate boards.
Subsequently, this story was included in tales of 1,001 nights.
Of course, this is nothing more than a legend. We know now that the magnetic mountain, i.e. mountains, rich loadstone, really exist - remember the famous Magnetic hill, where towering blast furnaces now Magnitogorsk. However, the force of attraction is like the mountains is extremely small, almost negligible. As such mountains or rocks, about which wrote Pliny, in the world never existed.
If you currently and ships are being built without iron and steel parts, they do so not out of fear magnetic rocks, and convenient for the study of terrestrial magnetism *.
Scientific novelist Kurt Lasswitz took the idea of the legend of Pliny to come up with a formidable military weapons, which in his novel "On the two planets come from Mars in the struggle with the earthly armies. Having such magnetic (or electromagnetic) weapons, the Martians don't even fight with the earth's inhabitants, and disarm them before the battle even begins.
This is how the novelist this episode of the battle between the Martians and the inhabitants of the Earth.
"The glittering ranks of horsemen broke rushed forward. And it seemed that the selfless commitment of troops finally forced a powerful enemy (the Martians. - Ya Ya) to retreat, as between its air ships there is a new movement. They rose into the air, as if about to give way.
At the same time, however, fell on top of some dark sprawling mass, now only appeared over the field. Like the fluttering veil, the weight of this, surrounded on all sides by air ships, quickly turned over the field. Here is the first number of riders fell in the area of its action, and immediately strange machine extends over the entire regiment. The action that produced it, was suddenly and horribly! From the fields came the shrill cry of terror. Horses and riders a ball lying on the ground, and the air was filled with the thick cloud of spears, swords and carbines, with thunder and crackling flying up to the machine to which they landed.
The car slid a little to the side and dropped her iron harvest on the earth. Two more times she returned and seemed to be mowed all on the field weapons. There were no hands, which would be able to hold a sword or spear.
That machine was a new invention Martians: she, with irresistible force drew to itself all made of iron and steel. With this floating in the air magnet Martians were snatched from their opponents weapons, not causing them any harm.
Air magnet swept further and approached the infantry. In vain the soldiers tried with both hands to hold their gun irresistible force pulled them out of his hands; many, still not producing them, were themselves keen on the air. In a few minutes the first regiment was disarmed. The car raced in pursuit of marching in the city of shelves, preparing for them the same fate.
A similar fate befell the artillery".
* In the program of the International Geophysical Year (IGY) in 1957-1958 from the Soviet Union participated this ship (schooner "dawn"), not exposed to magnetic forces; all fixtures, engine, anchors steel and iron replaced by copper, bronze, aluminum and other non-magnetic metals. (Approx. as amended).