Nikola Tesla, father of modern methods of generation and distribution of electrical energy, who was 78 years old yesterday, announced a new invention, or inventions, which he said, he considered the most important of the 700 made by him so far. He has perfected a method and apparatus, Dr. Tesla said yesterday ... which will send concentrated beams of particles through the free air, of such tremendous energy that they will bring down a fleet of 10,000 enemy airplanes at a distance of 250 miles from a defending nation's border and will cause armies of millions to drop dead in their tracks. This "death-beam," Dr. Tesla said, will operate silently but effectively at distances "as far as a telescope could see an object on the ground and as far as the curvature of the earth would permit it." It will be invisible and will leave no marks behind it beyond its evidence of destruction. An army of 1,000,000 dead, annihilated in an instant, he said, would not reveal even under the most powerful microscope just what catastrophe had caused its destruction. Dr. Tesla said this latest invention of his would make war impossible. It would make every nation impregnable against attack by airplanes or by large invading armies. But while it will make every nation safe against any attack by a would-be invader, Dr. Tesla added, the death-beam by its nature could not be employed similarly as a weapon for offense. For this death-beam, he explained, could be generated only from large, stationary and immovable power plants.