Now I know what a yoyo feels like, boinging up and down like a proper wotsit, until your head gets all wonky and your string gets proper tangled. You see, I fell down this hole right through the middle of the planet, then get yanked most of the way back again, then hurtled off down south again - back and forth, back and forth, gradually losing momentum until after about a week, or possibly six hours, or maybe two months, I finally came to rest, floating in the middle of the planet. In the dark. With my ears ringing. And feeling a bit sick.
It's dark here. And lonely. You might be wondering what it feels like to be at the centre of the planet, with all the gravitational forces pulling you in all directions, and the magnetic fields thrumming through your temples. Well, I wonder if you have ever been on a waltzer after you have drunk a lot of fizzy pop and had a hot dog that disagrees with you? Well, it's nothing like that. Of course, the real problem was that there was no realistic possibility of escape. Whichever way I went, north or south, it involved a climb of about four thousand miles, which I don't think I could manage. I didn't think my fingernails were up to it. I was reliant on someone lowering down a rope, which seemed unlikely.
Unless... No, on second thoughts, I'm not trying that again. I'm still writing letters of apology after the last time.
Then suddenly, and to my considerable surprise, someone switched on a light.