wind and cold; and they shrank from high and exposed, and
therefore really healthy, spots. But now that we have good glass,
and sash windows, and doors that will shut tight, we can build
warm houses where we like. And if you ever have to do with the
building of cottages, remember that it is your duty to the people
who will live in them, and therefore to the State, to see that
they stand high and dry, where no water can drain down into their
foundations, and where fog, and the poisonous gases which are
given out by rotting vegetables, cannot drain down either. You
will learn more about all that when you learn, as every civilised
lad should in these days, something about chemistry, and the laws
of fluids and gases. But you know already that flowers are cut
off by frost in the low grounds sooner than in the high; and that
the fog at night always lies along the brooks; and that the sour
moor-smell which warns us to shut our windows at sunset, comes
down from the hill, and not up from the valley. Now all these
things are caused by one and the same law; that cold air is
heavier than warm; and, therefore, like so much water, must run
down-hill."

"But what about the rainfall?"

"Well, I have wandered a little from the rainfall: though not as
far as you fancy; for fever and ague and rheumatism usually mean--
rain in the wrong place. But if you knew how much illness, and
torturing pain, and death, and sorrow arise, even to this very
day, from ignorance of these simple laws, then you would bear them
carefully in mind, and wish to know more about them. But now for
water being life to the beasts. Do you remember--though you are
hardly old enough--the cattle-plague? How the beasts died, or had