And still all this is nothing, or almost nothing, in comparison with the real power of the sun! The liquid state of the ocean; the gaseous state of the atmosphere; the currents of the sea; the raising of the clouds, the rains, storms, streams, rivers; the calorific value of all the forests of the globe and all the coal-mines of the earth; the motion of all living beings; the heat of all humanity; the stored-up power in all human muscles, in all the manufactories, in all the guns,--all that is almost nothing compared with that of which the sun is capable. Do we think that we have measured the solar power by enumerating the effects which it produces on the earth? Error! profound, tremendous, foolish error! This would be to believe still that this star has been created on purpose to illuminate terrestrial humanity. In reality, what an infinitesimal fraction of the sun’s total radiation the earth receives and utilizes! In order to appreciate it, let us consider the distance of ninety-three millions of miles which separates us from the central star, and at this distance let us see what effect our little globe produces, what heat it intercepts. Let us imagine an immense sphere _traced at this distance from the sun_, and entirely surrounding it. Well, on this gigantic sphere, the spot intercepted by our little earth is only equivalent to the fraction 1/2,138,000,000; that is to say, that the dazzling solar hearth radiates all round it through immensity a quantity of light and heat two thousand one hundred and thirty-eight million times more than that which we receive, and of which we have just now estimated the stupendous effects. The earth only stops in its passage the _two thousand millionth part of the total radiation_. Sometimes the storms or outbursts come in the shape of a bright spot instead of a dark one. [Illustration: A SOLAR ERUPTION.] Two astronomers were one day watching the sun from two different observatories, when they saw such an event take place. An intense and dazzling spot of light burst out upon the surface of the sun--so intense, so dazzling, as to stand quite apart from the radiant photosphere. To one astronomer it looked like a single spot, while the other saw two spots close together. In about a minute the light grew more dim, and in five minutes all was over. But in those five minutes the spot or spots had traveled a distance of thirty-five thousand miles. It was a very remarkable thing that the _magnets_ on earth--those delicate little needles which point so steadily yet perseveringly towards the North Pole--seemed to be strongly agitated by the distant solar outburst. This brings us to another interesting fact.