Because the attractive power lodged in the nucleus acts with most force on the largest masses; even as the rock is not so likely to leave the earth in a wind-storm as the dust; and in the flight of the comet through space, at the rate of three hundred and sixty-six miles per second, its lighter substances would naturally trail farthest behind it; for-- "The thing that's heavy in itself Upon enforcement flies with greatest speed." And it would seem as if in time this trailing material of the comet falls so far behind that it loses its grip, and is lost; hence the showers of _meteoroids_. Another says: "I can not accept your theory as to the glacial clays they were certainly deposited in water, formed like silt, washed down from the adjacent continents." I answer they were not, because:-- 1. If laid down in water, they would be stratified; but they are not. 2. If laid down in water, they would be full of the fossils of the water, fresh-water shells, sea-shells, bones of fish, reptiles, whales, seals, etc.; but they are non-fossiliferous. 3. If laid down in water, they would not be made exclusively from granite. Where are the continents to be found which are composed of granite and nothing but granite? 4. Where were the continents, of any kind, from which these washings came? They must have reached from pole to pole, and filled the whole Atlantic Ocean. And how could the washings of rivers have made this uniform sheet, reaching over the whole length and half the breadth of this continent? 5. If these clays were made from land-washings, how comes it that in some places they are red, in others blue, in others yellow? In Western Minnesota you penetrate {p. 403}