I am an emew, and my range is from I to 16,000,000. I am a little longer than a grain

I am an emew, and my range is from I to 16,000,000. I am a little longer than a grain of corn, and I am reckoned to be in number about 700,000,000. I am a very swift, and a very gentle, emew. I am always in the same place, and always in motion. I am never out of doors, except when you see me, and then I am only delivered from one part of my task to another. I am always in the same, and I am never in the same, I am never, I think, in any one place, but I am always in a great many. I am never, in the winter, in the summer, nor in the day, but I am always in