the colder months of the winter out of the reach of frost and snow. Our planet as you are aware, is peculiarly rich in caverns, owing to shrinkage of its surface rocks.
In some regions, exposed to cold now and then, but not perpetually covered with snow nor exposed to frost, the milder portions of the temperate zones north and south free use was made of hand dynamos. When the housewife wanted a fire someone had to work vigorously in turning a wheel, the muscular force of a man being transformed into electrical force and released as fire. In these regions chemical electricity was used us a weak lighting power. Asses sometimes worked all day charging accumulators, and when a wind blew there were thousands of sails to catch it. In spite of all that could be done, however, human life could not be supported beyond the fiftieth parallels of latitude north and south. This caused an over crowding of the temperate and tropical regions, and made the struggle for existence very intense. The food-producing area became too small, and the means of sustaining life fully could only be gained by those of strong hand and superior brain. Millions of the weaker men and women had their lives shortened by semi-starvation, and millions more died of diseases caused by cold. The people lost, courage; the marriage rate decreased very much; the death rate increased continually; the birth rate decreased; and during a single century the population fell off to the extent of one-sixth, that is, at the end of the century we were fewer by five hundred millions than at the beginning. Going on at this rate we should soon have had a small population living in the equatorial regions, and no more. Although we have had a hundred happy and prosperous centuries since that doleful time, that century is still remembered as the 'Black Century.'
We now come to the greatest discovery ever made upon this planet.
It was made by accident.
Most of you know more or less of it, and we all benefit by it, and our posterity to the end of time will continue to do so.
You know that several of the caverns in the north go to a great depth, and that some of them extend scores of miles underground; that in some there are lakes and rivers and vast spaces in which the air is pure and never falls below a comfortable temperature.
In one of these somewhere about one hundred thousand people had prepared their winter abode. Bedding, warm clothing, food, and as many necessaries as could be transferred from the homes for a score of miles round had been carried into the silent depths of one of these great caves. The people, bound together by a common difficulty, made their burdens lighter by sharing them. The strong helped the weak; those who had plenty shared with the sick, the needy, and the aged. We had already reached a high stage of civilisation, and life generally had become altruistic. No one lived for self alone, or sought to profit by the loss of another.