The sailors began leaping from the ship to a large rock that rose out of the water about half a mile off. Their agility was marvellous, and Flathootly covered himself with glory in leaping over the ship hundreds of feet in the air and alighting on the same spot on deck again.
Their officers and scientific staff remained on deck as became their dignity, although tempted to try their agility like the sailors.
Flathootly surprised us by leaping on a yardarm and exclaiming: "Gintlemen, I tell ye what it is, I'm no weight at all."
"How do you make that out?" said the professor.
"Well, Oi've been thinking," said he, "that, as you say, we're in the middle of the two wurrlds. Now it stands to sense that the wan wurrld, I mane the sun up there, is pullin' us up an' the t'other wurrld is pullin' us down, an' as both wurrlds is pulling aqually, why av corse we don't amount to no weight at all. How could I turn fifteen summersaults at wance if I was any weight? That shows yer weighing machine is all wrang again."
"How can you stand on the deck if you are no weight?" inquired the professor.
"Why, I'm only pressing me feet on the boards," said the Irishman; "look here!" So saying, he leaped from the yard and revolved in the air at least twenty times before alighting on the deck.
"Now," said the professor, "I'll explain why you only weigh seventeen pounds as indicated by the spring-balance. We have sailed, down the gulf 500 miles, haven't we?"
"And here we are sailing upside down on the inside roof of the world----"
"Sailin' upside down? Indeed, sorr, an' ye can't make me believe that, for shure I'm shtandin' on me feet like yourself, head uppermost."
"Well, whether you believe it or not, we are sailing upside down, just as ships going to Australia sail upside down as compared with ships sailing the North Atlantic. But the point of gravity is this: Here we are surrounded on all sides by the shell of the earth, which attracts equally in all directions. Hence all objects in the interior world have no weight as regards whatever thickness of the earth's shell surrounds them. You see, weight is caused by an object having the world on one side of it. Thus both the world and the object attract each other according to the density and distance apart. What we call a pound weight is a mass of matter attracted by the earth on its surface with a force equal to the weight of sixteen ounces. A pound weight on the surface of the earth weighs sixteen ounces, and all the mighty volume of our planet, with all its mountains, continents and seas, weighs only sixteen ounces on the surface of a pound weight. The earth may still weigh many millions of tons as regards the sun, but as regards a pound weight it only weighs sixteen ounces."