"Here in America we had to have a greater production to supply our huge population. It was a pure case of necessity. So we had to employ artificial heating during the night. "If we start sinking a shaft into the earth, the heat increases rapidly as we go down--more quickly in some parts of the world than others. On an average, the temperature rises about one degree Fahrenheit each 100 feet of depth. We found it economic, therefore, to use the earth's own heat to heat our farms. "By means of high speed drills, we can cut a three-foot shaft 3,000 feet deep in the earth in less than a month. We go down until we strike a temperature around 100 to 120 degrees Fahrenheit. Then we lower steel tanks into the cavity and run pipes up to the surface. The tanks are filled with water and two larger pipes run from each tank into the circulating system of pipes, around the lower walls throughout the length and breadth of the farms. The shafts are then closed at the top and we have a circulating system that is both cheap and efficient. The hot water continually rises into the pipes and circulates. As it cools, it flows down again into the tanks, where it is reheated and rises again. Thus the temperature of our farms is uniform all the year around and plant growth is as rapid during the night as during the day. "Heat alone, however, is not sufficient. We should still get only a normal growth. We wanted five crops a year. I put my research forces to work studying fertilizers. While the old nitrogen fertilizers were excellent, they were not suitable for high pressure, high speed growing methods. We evolved chemicals which were both cheap and easy to apply. We found that small quantities of _Termidon_, when mixed with water and sprayed over the field by overhead sprayers, which you will see running along the ceiling, would accelerate the growth of the crops enormously. "This liquid Termidon is sprayed over the entire length and breadth of the field before planting time, so that the soil becomes well soaked. The Termidon immediately turns the soil into a rich, dark strata, the best soil for potatoes, wheat, or corn. No other fertilizer need be used, the Termidon, applied after every growth, giving the soil all the vitality necessary." They were now in the field, when suddenly Alice asked: "What is the peculiar tingling in the soles of my feet, I feel as we walk along? You are using some electrical vibrations, I suppose."