Electrostatic effects are found to be usually characterized by very large potentials or voltages accompanied either by small currents or by currents that last for a very short time. A spark lasts less than one-tenth of a second and sometimes as little a time as a millionth of a second. However, two large spheres separated by a distance of one centimeter have to be charged to a potential difference of 30,000 V, at least, before the electrical intensity is sufficient to force a spark through the air resistance. If the spheres are separated by a distance of, say 40 cm, the potential difference must be nearly a million volts, only then will a spark pass.

All know at present, that lightning is a gigantic electric spark between charged clouds or between a charged cloud and the ground. However, there was a time when lightning was a subject for legends, an insoluble problem that scientists vainly tried to explain.

Benjamin Franklin, the great American scientist and progressive statesman, is acknowledged to be the pioneer of the theory of atmospheric electricity. In 1752, at Philadelphia, he flew a kite to draw down the lightning from the clouds to the earth and prove it to be electricity. In his famous kite experiment, he demonstrated that atmospheric electricity and static electricity is one and the same thing. And it was he, too, who was the first find the ingenious defense against the destructive action of lightning, — the lightning rod. Franklin was not only an outstanding scientist but also a true friend of the people. He has always been highly appreciated in Russia.

 Franklin's achievements were analyzed and approved by Lomonosov who had made his own experiments independently.