Why Do My Teeth Chatter? Your teeth chatter because when you are cold in a way that makes your teeth chatter the little muscles which close the jaw act in a series of quick little contractions which pull the jaw up, and then let it fall by its own weight. This is repeated many times and, as the action is quick, the chattering occurs. It is a peculiar thing that this occurs in spite of the will or brain, when, as a matter of fact, these muscles which operate the jaws are especially under the control of the brain. The chattering is really a spasm caused by the cold, and all spasms act independent of the will. Cold seems to act on the jaw muscles a good deal like some poisons which cause spasms. Where Did All the Water in the Oceans Come From? No, it did not come from the rivers which empty themselves into the oceans, because the oceans were there before the rivers existed. Part of it comes from the rivers now, but only a little in comparison to all the water there is in the ocean. I will try to tell you simply how all the water got into the ocean. There was a time when there was no water on the earth at all. That was when the earth was red hot, just as it is to-day on the inside, and at that time all the water we have to-day was up in the air in the form of gases. Strange as it may seem to you, if you take two gases, one called hydrogen and the other oxygen, and mix them the right way, they will turn into water, and if you had the right kind of chemical apparatus you could take water and turn it into these gases again. When, then, the earth was still all red hot, all of our water was up in the air in the form of these two gases. Then, later on, when the amount of heat on the earth was just right to make these gases mix together, the water came down out of the air in great quantities, and there was so much of it that it completely covered the whole earth and no land was visible. Later on, for various reasons, mountains were thrown up on the earth’s surface by great earthquakes, and every time a mountain or a high place was formed there had to be a hole or low place some place else, and the water ran into these low places and stayed there, and that uncovered more of the land, because there wasn’t enough water to fill all the holes and cover the land too, and that is what makes our continents and islands and all of the land we see. There is now about three times as much earth covered with water as there is land. Of course, the sun is always picking up water through what is called evaporation, which means that it is taken into the air in the form of gases. Later it comes down again in the form of rain and falls into the oceans or on the land, where it sinks in, finally finding a stream or river, and sooner or later gets back into the ocean again. Why Don’t the Water in the Ocean Sink In?