say, if one body weighs twice as much as another (or, more properly speaking, if it contains twice as much matter as another) it will have twice the power of attraction.
"Now I weigh a great deal less than the earth does, and consequently the knife will fall toward me a great deal more slowly than it falls toward the earth. Ah, 'now goes me a light up!' as our German professor used to say. The earth must weigh over a trillion times as much as I do, and consequently, since it would take a second for the knife to fall sixteen feet on the earth, it would take—a trillion seconds for it to fall to me. Now a trillion seconds represent many thousands of years, so that if I want to wait until the knife is attracted to me, I shall have to stay in the same spot here for thousands upon thousands of years, and I'm afraid I have n't the time to spare just at present."
William had hit the nail on the head this time, but he had greatly underestimated the time that would be required. The density of the earth is five and one half times that of water, and our planet, therefore, weighs five and one half times as much as a globe of water of the same size. The diameter of the earth being about eight thousand
